That sounds reasonable, but I wouldn't get hung up on set numbers. At that age he should get two bug meals per day. Offer him as many dusted crickets as he wants in about a 10 minute window or until he loses interest. You'll find that his appetite will fluctuate quite a bit over time so some days he will eat a ton of them and some days he won't show much interest and that's OK. For planning purposes, I usually ordered about 1,000 crickets per month with a dragon that age (eaten and die offs).