Answer

That God decided to create time and to create something first in time in no way disproves his existence. You seem to indicate that because God has no limits, he must constantly be creating something. If that were so, then he would be limited to having to be creating. He would not have the freedom not to create. God has total freedom. Nothing says that he has to be constantly creating things. He exists outside of time. You write as if he operates in the world of time that we know, but he exists in an eternal now.