Not to be redundant but i do think talking to the daycare is a good idea.
I worked in a 2 year old room a few years ago as an aide, so i didn't get filled in on who initiated potty training, but most daycares sort of have a schedule for toileting/diapering, you could request that they sit him on the potty for a few minutes each time before they change him.
I feel soooo strongly about this---kids are generally NOT going to tell you they need to go, or suddendly decide to stop playing if You ASK them if they need to. I think the very very best potty training advice is to JUST TAKE THEM TO THE POTTY. Figure out a schedule and take them, at home with my kids we went when we woke up, before morning snack, before lunch, before nap, when we got up from nap, before dinner, and at bed time, It worked out to be roughly every two hours, they might not always go but at least it was just part of their day and not a stuggle or power issue to go when they were engaged in an activity. sorry for the rant.
one other idea for day care, if you see that he is really doing well, or if they are really cooperative, you could put real undies on under his pullups, so he feels they are wet, or buy the plastic undies that are waterproof but plastic on the outside, OR you could always do that at home for a while Then introduce it at school. Just go easy on the teachers, they have a lot of kids to take care of and changing pee pee undies every 2 hours probably won't be a whole lot of fun for them. so make sure he is doing well first.
Those teachers want your child trained, and will most likely be very helpful because in the long run it makes their life much easier. be sure to share with them if you notice that he has a regularity to his wetting or bms, like if you give him juice at breakfast does he usually have a dry diaper at 8 am but a wet one at 9 am? that sort of thing, The teachers might also be able to help track that as well, since I know we had to note the times of diaper changes and if the child was wet or dry.
sorry this was so long, hope things go well for you. Just remember that your son will be out of diapers in no time, even if it doesn't seem like it.