A two to three month old should be eating all the small feeders that he wants....just don't leave them in the enclosure with him over night or they may eat on him. I'm in the US and feed crickets, flies, baby worms and baby dubia. I'm attaching my blog for new keepers below.
Yeah, as jannb says, as many small feeders as he'll eat. So he'll GROW GROW GROW!!! LOL
Simba (my 3mo) is on fruit flies, small dubia roaches, small morio worms and wax worms as an occasional treat. I will get him some tiny locusts at some point and am thinking of trying him with bean weevils too. When he grows I'll feed him the larger versions of the above (apart from the fruit flies and the bean weevils as they just stay tiny) as well as butterworms and silkworms.
I don't think I've left any out LOL (I don't feed crix as I can't abide their smell and they freak me out)