How old is my bearded dragon?

[Flapjack6260]

I got my bearded dragon a little over 2 weeks ago from Petco. I forgot to ask how old he was though. (They probably wouldn't know anyways) Here is a picture of him next to a 6 inch ruler, so he is about 12 inches long from nose to tail. He eats a diet of 30-40 small Dubias a day and he has been growing like a weed! I want to know how old he is so that if I have any health concerns, I will know his age to tell the Vet.

 

[AHBD]

He looks great and is the size of an average 3-4 month old. Their sizes do vary quite a bit, so again, that's an average.