What sort of hours are you working, and how many days a week? I typically go back to work early (at 6 weeks, 7 weeks and 12 weeks for my 3). I'm out of the house from 8-5 (or so), and I would give my babies 3 bottles when I was gone, roughly at 10, 1, and 4 (of 4-5 ounces each) with a wakeup feed at 6:30/7. If they weren't making it to 3 hours between bottles, I would feed soon after picking up, so I didn't have to prepare an extra bottle. Mine were also ebf/ebm for 6 months (and still pumped/nursed for some time after that too). Since I find pumping at work a total pain, I've managed to pump at 11 and 3, which is a typical feed time for a 4+ month old, and I found I could get enough milk for 3 bottles at just those times. You could just as easily pump when you expect to give a bottle when you are gone, at 10, 1, 4 or so also.
Nights vary with my LO's between feeds, from anywhere of 1 nf to up to 3 nf at that young age, with slowly reducing them as they got older, based on routine and other things that tend to impact nights. The first few months are hard with tons of nw's, hopefully they'll start sorting themselves out soon as your LO gets older.
