G.J.
Trust me, you won't be the 1st to tough it out and then let the tears flow once you're in the parkng lot, heck many of us couldn't even make it that far! It is tough leaving your 1st born for the first time; however, if he enjoys 'school', reading, crafts stuff, it will just be a matter of a few days of going and he will realize that this is a fun place to be and Mommy always returns when he is all done and you need to remember that he is going to get outside influences from here on out and that can be a great thing. It is hard, because you have to 'let go' a bit. It's like lettting the apron strings loose just a little bit. But it is all part of him growing up and becoming the little man you want him to be.
I think my 1st son cried for a little while the first few times, the teachers were awesome! they took him and stayed with him until he felt comfortable enough to go off and play on his own. and he would only cry for a very short time.
But do be prepared to have that heart wrenching feeling when and if he even cries. My 2nd son, after watching his big brother go, barely even remembered to give me a hug and kiss before he went bolting into the classroom - he was soooo ready! that almost broke my heart too, I almost felt like he didn't need me anymore.
anyway, i hope my ramblings comfort you somehow, knowing that other Mom's have the same feelings over this situation. I think just continuing to read books on going to school help alot. 'Froggy goes to School' is fun too. and the Berenstein Bears have a book for just about every topic imaginable, I'm sure there is a school one too! Probably a dentist one also...
He will be fine and think of all the new things he will learn, you will be so proud of him.