He may have picked up some anxiety from you over the last weeks because I'm sure getting everything ready has been a bit stressful. Also leave as many of his toys in his room or away during the day and buy new toys for the daycare so he isn't sharing his toys he is sharing your toys. Just as we can only cater so much to new kids coming in it is also important from the beginning to establish some rules for our own kids with the idea ok this is now what your life is going to be like and while you don't have to like it you have to accept it and live within these boundaries. I would think the beginning will be rough but once you get the kids there and he starts to see how much he gets to do because of them, the amount of time you spend doing stuff with them it should get better soon. If he is two and has had very little exposure to other kids then that is the part you will need to work on in the sense of he doesn't know what it means to have someome come to play and stay for lunch as it doesn't mean they replace him and he goes away or whatever might be going through his mind. Consider having some treats like cookies for snack or lunch or favourite foods of your son - things he can look forward to.