Kids don't like change, and this is a big one. That said, they are also adaptable and will adjust. Give him time; its only been one day. If he doesn't want to be alone in his room, don't make him for now. I know we slept on the floor of my daughter's room for a couple of months after we moved into our new house. Not fun, but seemed like the right thing to do for her. Also, remember that moving days are stressful for everyone (including you) and he's probably picking up on that stress. When his toys are back out, there's food in the house, and there's other stuff to make it feel like "home" he'll get better. He's still so young he probably won't ever consciously remember living with your mom. The first few weeks might be a little rough, but then your apartment will be just as much home as anyplace else and he'll be fine. Good luck!