You should be feeding everyday about 15-20 crickets until you cham is an adult, usually people start cutting back on food for males when they turn a year old and other wait between 12-18 months.
Of course, very small crickets, with calcium powder (no d3 every day, with d3 twice a month, multivit once a month) Gutload on leafy greens (mostly, some carrot, fruit etc.).
Seriously, get some fruit flies as well- they are easy to keep, you can transfer some to a new pot for breeding more, Reptar will go nuts for them......