L._.
I agree with keeping the drop off very short, no matter what. I also agree with calling a few minutes later. Most kids stop within minutes. I've seen some stop before the mom even gets the car started.
Another thing you can do is laminate a picture of you and him and hang it on a string so that he can wear it. If they don't want him having it around his neck, you can get one of those buttons that you put the picture into. Hobby lobby would have personalized pin makers. Let your son keep this picture so that he can be reminded that you will come back and the two of you will always be together.
Another thing you could do is bring some treats for the whole class. Let your son know that he will be able to give them to his friends. That may make him feel real special. Let him bring in the cookies or whatever you choose.
Mostly, you should feel good if the place your son is going has a good reputation. It's all so very normal. Just keep in mind that all kids have their own personalities. I have seen kids that belong in a center. I've seen kids that belong in a home situation. I've seen kids that were difficult to please no matter how hard we tried and yet the same child would be pleased as punch with someone else. The funny thing about kids is that they can dislike a grown up and not know why or not be able to put words to it. I used to have a little girl that I homeschooled for half a school year for her parents. The child was 8 and she would get a migraine at school when she wasn't sick. It started happening everyday. So she would come to my house and be all better within minutes. We decided to homeschool her because she was deathly afraid of her school. Later on down the road she admitted to me that she was afraid of the school principal. She described the woman to me as a black woman with really tall big hair that was dyed bright red. She said she wore a lot of makeup and that she had a lot of jewelry on and really long fingernails. She said the woman walked around the school all day long and was in and out of the classrooms and scared her. She never once told me anything the woman said that scared her. It was all about how she looked.
If your son is not complaining and is happy within minutes it's probably okay. But try and talk with him about the school and his day so that you can make sure this is the place for him. No child should be stuck in an environment that is too much for them.
Suzi