K.,
First of all I think that you are doing is a GREAT thing. My husband and I have often said that when our boys are a little older that is something that we would love to do.
Newborns are difficult, especially when they are challenged right away, as yours has been. Both of my boys were 4 weeks early, but able to come home right away. I had them on a "schedule" from the first day home. Do not put cereal in his bottle unless the doctor tells you to. His little tummy isn't ready for it yet. Don't wake him up, he is sleeping because he needs to. In the evening, do the exact same thing everyday......bathe him, get the jammies on, then the bottle. Do a little snuggling, maybe read a short bed-time story and them lay him down. Try to keep that time as quiet as possible, and as little light as possible. Unless it is absolutely neccessary, don't go anywhere that will have you home later than the "bedtime". Even as young as he is, he will start to recognize the time of day by the things that he does and the places he is. My boys are 6 and 3 and the ocassions are extremely rare that we are not at home, getting reay for bed at 7:30. They were both sleeping through the night at 8 weeks.
you may have some family and friends that get a little upset when you tell them that you need to leave, or can not do things, because of the schedule, but trust me, it will be better for you and the children in the long run.
Best of luck.