Can I travel to the US after I received my police clearance from FBI, in the midst of my application for Express Entry? Or should I wait until I submit e-APR?
AFAIK You will need to get a new FBI PCC in case you visit the US post getting the PCC. Better to travel post AoR. I advise you to search some more on this forum to confirm.
From what I understand, if you have submitted your application already. Then, it won't be a problem.
But if you have not submitted your application post ITA then you need to again get your PCC because the requirement is for PCC to cover your last exit from that specific country.
Hope it helps, further wait for senior members to respond.