J.C.
Hi L.,
Try to bring an item from home that he is most comfortable with. When my daughter started daycare for the first time, I brought her favorite bear. It can be almost anything he is attached to, his favorite truck, bear, blanket? It's more of a comfort zone for him. Tell him that if he misses mommy or feels sad or scared, he can use this to comfort him and make him feel better. Also, it takes about 2 weeks or so for them to get used to the new environment and the new kids and teachers around them.
After you try that, for the first week, I'd call in and check on him at least once a day... Then maybe one day in the 2nd week just drop in and peek to see how he is doing, this way you can see it for yourself. I did that with my daughter and she adjusted really well.
Another thing you can do is when you pick him up after work, maybe get his favorite snack to give to him when you pick him up. Something "special" for him.. Then praise him that what an awesome job you did today at daycare! This way he can always look forward to the next day. (It might take a couple weeks for him to realize that though, just keep it strong, and don't worry too much) since kids sometimes still do feel what their mom feels.
Hope this advice helped! Keep us posted!
J.