hiya,
my little boy was 12 weeks early and to tell you the truth it took him 7 months until he slept through from 11 till 6, I think with their tummies only being very small they have to eat often. I would say feed very strictly during the day, getting as much milk into lo as possible then let him set the pace for the night, but it probably will take quite a while yet.
On the other hand my little girl who was only 5 weeks early was sleeping through from about 4-5 months.
hope this has helped abit.
oh Has the neonatal team gave you a summary of the amount of ml's of milk he should be having?, when My little boy was in nicu it was 150ml per kg of weight per 24 hours( mind you I think that was EBM) . If you can work this out then you will know what he has to get, unless you are breastfeeding of course.