@lovemyfamilyg all preemie's are different. For example my 29 weeker was practice nursing at 32 weeks gestational (3 weeks old) but we didn't actually breastfeed until he was 35 weeks gestational (6 weeks old). Practice sucking as @mrsgeorge mentioned is for the preemie's to get familiar with breast, but since they're still little they still need the tube to get the milk from, that way doctors can measure the amount of milk babies are getting. When babies are in the nicu everything going in (milk, fortified milk, or formula) and everything going out (pee and poo diapers) all get weighed so they can keep track of growth, so the little ones have to have everything taken in measured so they don't get to start off doing actual breastfeeding sessions, although they can get some milk out, but to do the non nutritive sucking moms usually have to pump first so we don't give the baby too much milk at first. Phew! That was a lot to say, but when you have a full term baby they usually try to get babies to nurse shortly after delivery. Sorry to steal your post MrsGeorge.