Q:

How did Lore summon the Crystalline Entity when he was dismantled at the time?

It is postulated in this answer that the Crystalline Entity must have visited the colony twice for Lore to have known about and been able to contact it. However, we know that Lore was disassembled long enough for Data to be constructed, which presumably takes some time, and interact with the colonists for a time before he was put into his hibernation state and left on that pedestal where he was found by the crew of the USS Tripoli. So, how was the deactivated, and disassembled Lore able to contact the entity at all? The timeline for that isn't quite adding up for me.

A:

Here's the timeline I compiled from looking at the transcripts of various episodes. 
Since it's never addressed directly in canon, we have to try and fill the gaps ourselves. I try to keep speculations not backed by the canon to a minimum.
There are some reasons to believe that it took some time before the entity arrived, and there are other reasons to believe that building Data did not take very long. So if you squint really hard and tilt your head sideways, the timeline might almost not include any plot hole.
To summarize:

Lore has contacted and summoned the Entity before he has been disassembled. He had knowledge of the Entity from its previous visits to the colony.
It is unknown where the Entity was during the contact with Lore, but there might be reasons why it didn't immediately come to Omicron Theta.
Constructing Data might have been done quickly due to Soong's talents and the availability of spare parts
Data wasn't even fully finished when the Entity finally attacked

We know the Entity visited Omicron Theta multiple times before killing everyone.
As you pointed out, the fact that the Entity has to have visited the planet before was already discussed in this answer. 
Lore communicated with the Entity before he was disassembled

LORE: And let us toast also the great Crystal Entity with whom I learned to communicate. Before Doctor Soong disassembled me, I earned its gratitude by revealing the way to the colonists. Can you image its gratitude when I give it the life on this vessel?

(TNG: Datalore)
This is the answer to your question: He summoned the entity before he was disassembled. But how does that fit into the rest of the timeline?
The entity may have many reasons to be delayed
This part is speculating a bit, as I try to find reasons why there might have been a significant delay before the Entity arrived at Omicron Theta.
If the Entity's beam which we see on-screen is its only way of feeding, devouring an entire planet will take a lot of time. We can infer that the entity usually finishes "eating" once it starts, as it usually leaves no witnesses to tell the tale:

MARR: The Crystalline Entity seems to function like a gigantic electromagnetic collector. It needs a lot of power to keep going so it strips every form of life from the worlds it encounters and converts it all into energy.
RIKER: There's no vegetation, no insects, not even soil bacteria. It left nothing.
MARR: Except witnesses, for the first time in eleven recorded attacks. Now why, I wonder, did it spare your group?  

(TNG: Silcon Avatar)
It's worth noting that Marr is considered a specialist regarding the Entity, so her words carry some weight.
Also, we have conflicting accounts on how intelligent the Entity is. While Picard compares it to a Sperm Whale in the episode "Silicon Avatar", probably not aware of what it's doing while it feeds, Lore is having a one-way audio communication towards the Entity in a way that indicates a high level of intelligence in the Entity in "Datalore":

(Obviously, Lore is now impersonating Data and has donned his uniform)
LORE: Crystal Entity. Upon arriving here you can identify me as the machine named Data. (door bell) End of message. 

(TNG: Datalore)
If it's intelligent, then there would be even more reason to believe that the entity is following its own agenda and might not come running directly when being called.
The tricky part of building an Android is not the body itself, and Soong is very, very good at building androids
It's well established in the Canon that  it's the positronic net what makes creating Androids so difficult. In comparison, the life-like looks seem to be easily achievable.
I am now speculating again in that I propose that Soong had no difficulty at all in creating Data's body. Heck, for all we know, he might have had the parts lying around from the creation of Data, Lore, B4 and their two siblings. The fact that there were three Androids before Lore is stated in "Inheritance":

DATA: I was not aware he created other androids before my brother.
JULIANA: There were three of them. They were like children to us. Losing them was very painful. 

(TNG: Inheritance)
There is another hint in the canon on how long it takes to create an Android body.
Even though we don't have a reliable timeline, when Data builds his daughter, Lal, in TNG: "The Offspring", it seems that creating a lifelike exterior does not take a lot of time.
So if the body is not the problem, let's take a look on Soong's abilities to build positronic brains:
After his wife was injured, he was able to create another, extremely life-like Android in the time his wife was in a coma, and that while his resources have been very limited on the planet he fled to.
Here's the relevant part of the transcript:

SOONG: She was injured when the Crystalline Entity attacked. We made it as far as Terlina Three but, she slipped into a coma. When I realised nothing could be done for her, I built an android. I tried to perfect my synaptic scanning technique so that I could transfer Juliana's memories into a positronic matrix. I didn't know if it would work, but I had to try. I couldn't stand the thought of losing the only woman I ever loved. A few days after Juliana died, I activated the android. She looked up at me and smiled. She recognised me. It had worked! Here was a life not two minutes old, and as far as she knew I was her husband. She'd just recovered from a terrible injury. It was incredible.

(TNG: Inheritance)
(Apart from proving his amazing skills, this also shows that it's possible to create an android that appears to be lifelike with limited resources)
Data wasn't even finished when the Entity attacked
On top of Soong being very good at what he was doing, he might even not have been really finished with Data when he left Omicron Theta. It looks as if he has been interrupted in the process of finalizing Data:

JULIANA: That's what I called it. You were like a baby, at first. A hundred kilogram baby, but still. You had trouble learning your motor skills, learning how to process sensory information. And of course Noonian was never satisfied. He kept tinkering, trying to make you as human as possible.
DATA: So you wiped my memory processors after this childhood.
JULIANA: Then we deactivated you and programmed you with the colonists' logs. We had planned to reactivate you, but we never got the chance. That's when the Crystalline Entity attacked. We had to leave quickly. We wanted to take you with us, but there was only room for two in the escape pod.

(TNG: Inheritance)
At this point, it wasn't even clear (to Julianna) whether or not Soong's plan to create an Android without emotions had succeded. This is speculation now, but I would take that as another piece of evidence about how unfinished Data was at that point.

JULIANA: I lied. When I said there was no room for you in the escape pod that we took from Omicron. There was. I didn't want to bring you with us. I was afraid if we reactivated you, you'd turn out like Lore. I made Noonian leave you behind.

(TNG: Inheritance)
Taking it all together, if we assume that the Entity didn't come to Omicron Theta right away, and if we also assume that Soong was very quick with building data, the timeline holds up. 

