Don't know if I'd feed em corn yet at 5 weeks. Softer treats usually at that age. Breads fine, though white bread doesn't do much nutritionally. Empty calories, but ok once in awhile. Be sure to give em access to grit if your giving them something other than soft stuff like yogurt.
I give little bread crumbs at a few weeks and meal worms-They fight over them and its so funny! They love yogurt too. I would also wait on corn. Be careful if feeding mealworms because if you are raising for show the protine will make the combs grow pretty fast.