Arriving EWR at 11 AM on a Tuesday morning on AA flight and connecting to BA flight departing EWR at 6:25 PM.

I am AC member....I'm assuming I can access AC after deplaning 1st flt and hang out for couple of hours before taking AirTrain to Terminal B. Our flights are in FC.

Given that I want to access the BA Galleries Lounge which opens at 3 PM when should we think about leaving TA for TB and how busy is security for Terminal B between 1 and 3 PM?