Prof. never responded to email about LoR I am in community college, and I emailed my calc prof a few days ago asking if he could give me a LoR so I can transfer. 

I'm not close to him on a personal level, but he knows who I am and I have been involved in the class (going to office hours, attending review sessions, sitting in the front, etc.) I also gotta B in his class. I mean I could go ask one of my English profs, but as a Comp Sci major I feel asking a math prof would be best. Plus he knows this is my second attempt at Calculus. 

The very main reason why I am asking him is because he is an alum to the school I want to transfer to, and which I am asking a LoR to. But also, he is the only prof that I have been somewhat willingly involved in the class. 

He hasn't responded to my email for a few days, should I give it more time? He has office hours tomorrow, but I don't want to take it away from the students using it for review for our finals next week. Should I wait till after finals to follow up? This isn't a university I'm at, it's only community college so like the classes aren't that big, so he know who I am and stuff. It's not even due until June 1st, but the admissions is rolling admissions so it's not the decisions are all out at once. So I just think I'll set the due date to a month whenever after he agrees to do it. 

I've never done this before so I have no idea any criterias or anything. I just know that I should give him a decent amount of time, and have been told about a month seems reasonable.
Some people answer emails the next day, some after a few days, and some forget about all emails that they do not answer immediately. 

As a rule of thumb: I would write a gentle reminder after about two weeks. If he still does not answer, I would try to meet him in person. If you yourself are under time pressure to get the LoR, then you might need to react sooner.