C.P.
Hi A.,
You just need to give him some time, he will eventually get over it and then your heart will really break when the day comes that he's like "mommy who?" when you drop him off! :-)
We started my 2 year old in daycare last month and the first three weeks were bad. She cried everyday that we dropped her off, she would grip so h*** o* to my shirts that I swear she was going to rip them off of me! A few times I hung around outside the classroom to watch after I left and within five minutes, she was over it. After her third week she was suddenly excited to be in school and she'd walk herself to class and not look back! She absolutely loves it and is doing so well.
So hang in there. It's very tough in the beginning and feels like they'll never stop crying when you drop them off. And for your son, it may be harder since he's only going to be going a couple days out of the week and it won't be an everyday routine for him. But I'm sure soon enough he'll make new friends and will love his teachers, and he'll adapt.
You can try leaving his favorite stuffed animal or something there for him, something he is familiar with. Drop by the school in the middle of the day and observe him. I'm sure you'll be surprised to see that he's being sociable and enjoying himself. A visit like this will make you feel much better!
Good luck!
-Char