If you order like 500 1/4 inch crickets for a 4 month old or so they will eat about 15-20 a day so they will last about 3 weeks as you will most likely have some die off. They will not be too big if you feed them off in the right amount of time. Plus your cham will grow too!!
yes, panthers can eat full size crickets but it depends on the size of a panther. not all panthers are the same size at every age. I would say by 7 months or so you panther could eat a full size cricket.