The gravel or grit is not really needed and can actually cause some problems. I raised a lot of budgies and cockatiels and never used grit or gravel. The only birds that need grit are chickens and doves and such that eat seeds and grain whole, and they don't need it all the time. Good luck with the little guy.
1.4 Ball Pythons,1.1 Greybanded Kings,1.1 Cal Kings,1.1 Brooksi, 0.1 Goini,2.1 Striped Motley Corns, 1.1 Normal Corns, 1.0 Ghost Motley Corn,0.2 Anery Corns, 0.1 Emoryi x Corn, 2.1 Western Hognose,1.1 Leucistic Texas Rats, 1.1 Mexican Black Kings