I think the main thing about having a goal for our children, is to remember that although the effort is up to us, the result is up to Hashem.
Absolutely, do whatever it is you think is best for you and your son, attempt to train him without guilt, and sign him up for your dream gan. Then allow yourself the luxury of not being stressed over the result.
If he doesn't train in time, it's Hashem's decision, and certainly not your failure: and it's the best thing for both of you, to be sure.
B'Hatzlacha! I've got an almost twosie boy who isn't quite ready to potty train....though he's fully aware of what he's doing, he's not interested in the potty, except to sit on it for a snack!!!
BTW: I noticed that he loves to ride on his bimba without the seat/lid, and I thought that would make a brilliant potty! I'm going to tell him to sit on the bimba and ride it around without the nappy on .... do you want to try it and see if it works?