Hi Brenda,
Until a few months ago, I was a wildlife rehabilitator in Oklahoma. I have just relocated to Texas and was browsing this site when I saw your post. Hope this helps.
As soon as your Little Fat Feather gets all of his feathers in, back off the feeding to about every hour. If he is perching, start to offer him a shallow dish of water on the ground. You really only need to feed him about 10 hours each day. As you steadily back off from hourly feeding, leave mealworms on a shallow glass or plastic dish on the bottom of the cage. As he gets hungry, he will start to pick at them. You can also help him by making him follow the mealworms in your finges and just lower them a bit each time until he is taking them off the ground out of your fingers.
Most important ~ he needs to learn how to fly. I suggest going to Family Dollar or the like and buying a screen picnic tent (about $30). Place SEVERAL things inside at different levels for him to perch on. Sticks & branches from the back yard are PERFECT. Leave him in it during the day with a GOOD water and food source. He won't be ready for that until he is fully feathered. (another week or two) As you observe him flying and picking up food on his own, you may release him. Be careful WHERE you release him, as he will undoubtedly be imprinted a bit to humans. You won't want him to land on someone's head and get smooshed. If you know anyone in the country with some land who can observe him for a while, that is best. If not, somewhere remote in one of the state parks is ideal. Just be SURE that you see other mockingbirds in the area before release. This will let you know that there is an appropriate food source for your little guy.
Feel free to contact me if you have further questions. Always happy to help our little critters.
Good Luck!
WildChild@laketawakoni.com