I went back to work when LO was 2.5 months, but starting pumping while on maternity leave to build up a stash.
My schedule right when I went back to work was to wake up an hour and a half before baby to pump. Feed her before I left for work. Pump 3x at work. Leave work right by 5:15 to get home to feed her at 6. Pump again at 11 p.m. before bed.
I try to do 2 15-20 minute sessions at work and one 10-minute session. I bring my lunch and eat lunch during one of the pumping sessions. But many times I can only pump 2x a day, I just make up for it by pumping at home.