being as your guy is only a month and small they would most certainly outgrow him before you fed them all (assuming you have no other reptiles)
crickets in general grow pretty fast, especially in warm areas, but they seem to double in size every week lol. I would say try to get like 250 at most the first time (even that may be to much) and adjust what you need from there.
Buy the smallest bulk order that you can, and order them 1 size smaller than needed. Because your cham is only 1 month old, I'd probably get about 250 or 500, but realize that you'll have to try to feed off the largest ones first to allow the smaller ones to grow up. Good luck!
Thanks for the offer. I see you are located in America, I think it was Michigan, and I'm located in Brampton, Ontario in Canada. I would totally buy some seeing as you are a reputable supplier, but wouldn't shipping be a ton? And is there a possibility of a mass die off in the shipping days?