My twin girls were premature, so my advice below is based on what I was told when they were in the hospital and by their pediatrician over their first year.
Babies are generally considered preemies when they're six or more weeks early. And most pediatricians say that preemies don't fully "catch up" for a year even if they appear developmentally ok. So, doctors and other people that care consider them preemies and thus subject to special consideration for a full year. The six weeks that most daycares use as their rule is six weeks from the due date. Therefore, you've got a few weeks until his due date plus the typical six weeks... so eight or nine weeks until a typical daycare would take him?
I don't love daycare for preemies (like many of the previous posters) but if that's your only option, then you'll make it work. Just be really aware of the risks of illness. If he's 10 weeks premature, how are his lungs? Will he qualify for RSV shots? (I would assume yes). Please make sure he gets the shots because RSV in a preemie can be disastrous. And talk to the pediatrician or other parents of preemies to get an idea of how much time you're going to have to take off for illness during the first year. I had a nanny -- it was the same cost as two infants in daycare -- but friends whose preemies went to daycare ended up taking weeks and weeks due to illnesses because many preemies are more susceptible. Any possibility there's an older lady in your neighborhood who could care for him for a few months until he's a bit older and his immune system is better developed? Someone at church who could help?
Whatever you decide, enjoy!