Sending a follow up email for a research assistant position I have submitted an application for a research assistant position in field of psychology and neuroscience  in the USA. The person to whom I submitted my application seems to be the lab manager (not quite sure though). Let's call this person A. But I also find the job posted under another lab member (let's call this person B). It has been 20 days since I submitted my application.

Should I send a follow up to person A?

What if I still do not hear back from person A after sending a follow up?


Or

Should I send an email to person B referencing that I have submitted my application on … to person A?

What is an appropriate amount of time to wait before send email to the PI of the lab inquiring about any opening her/his lab?


Note, my qualification does fit the job requirements. Also the job posting dated at the beginning of this year so there is a possibility that the job has been filled. In this case, can still express my interest in this job and ask to be considered for future opening?
Edit: please assume that the job has not been filled. Also there is no deadline for this job. They have something along these lines &quot;Job will be closed when the right candidate is selected.&quot;
The answer written here assumes the position is still open and they are still searching for candidates.
Send a follow-up email to person A, cc'ing B.
Then, give them one week to reply (I mean, wait one week, not giving them a deadline :) ! ). If they do not react, try to call them on the phone (A or B, they seem to be equally involved in the decision process).
It is by far less time consuming for both parties (you and A, or you and B) to discuss such a thing via phone.