My no longer 3 year old

So, Merrit turned 4 last Saturday. I don't know how I feel about this. Not at all. Let's just sum it up by saying that when his big boy backpack came in the mail, I cried. Seriously, cried. He is currently attending a day care, which provides pre-k (which he will be starting next year). The school where I work has just added a pre-k program this year. I have been back and forth and back and forth about what to do. It's like I know that the logical thing to do would be to bring him to school with me, but I just know that it's going to mean a HUGE change on both my part and his. He will no longer be coddled at day care from people who know and love him. He will now be part of something bigger, MUCH bigger. And I just don't know if I'm ready for that yet. While I continue to pray and ask for guidance on what to do, I think that the answer has already been given to me. I'm just not ready to accept it yet. I honestly believe that it lies in me letting go. I just don't know if I'm brave enough yet. He's my baby. Yes, he is 4, but he is MY baby. I love this child more than life itself and would do anything in the world to protect him. But am I protecting him, or disabling him?

This was his invitation, which I made myself, and was very proud of, considering that what I normally do is spend TONS of money for someone else to make it, for it then to be thrown in the trash by the recipients soon afterward.