Re: Going back to work soon - Start lo on schedule now?
congratulations on your new baby!
unfortunately what the PPs say is true: all too often pediatricians give advice that undermines breastfeeding. and new moms often trust doctors (as well they SHOULD be able to), and find themselves supplementing when they didn't mean to. scheduling feedings is one of the major culprits. it's important to feed on demand to help regulate your supply, long-term. remember that breastmilk digests extremely easily - that's why it's so good for babies - but it also means they might well be hungry every hour for part of the day! overfeeding formula can be a concern, but babies can't overeat on breastmilk, because as they get full they suck more gently and thus get less milk.
another piece of advice that often undermines breastfeeding is the "pump to see what baby's getting" advice. pumps are never as effective as a baby who is able to eat well, and many women don't respond well to the pump, so it almost always underestimates supply. that being said, getting 3 oz after 3 hours is pretty normal, and indicates that you don't have a supply problem.
as far as working etc - if you're like many moms and hate to pump - then it makes sense to minimize how much you need to. as to your question about the end of day, yes, it makes sense to try to nurse her at 4:45 instead of a bottle at 4:15. lots of moms leave milk in small quantities - 3 oz, plus some 1-2 oz topoffs - so if baby is hungry at 4:15 the day care provider can give just a little until you get there and nurse. lots of moms also find it easier to go home & nurse on lunch break instead of pumping, that reduces the total number of pumps, and nursing is better for your supply (and better for baby) as well as being more pleasant for most people.
good luck! keep asking questions here!
Nursing, pumping, cloth-diapering, babywearing, working professor mama with the awesomest SAHD ever.