every other day is a good rule of thumb i think.
At 2 inches I wouldn't go any more than 1 cube each other day though, you don't want him getting too chubby.
As he gets bigger I'd recommend earthworms, both small whole and cut up. It really is better nutritionally and they different it makes to their energy is dramatic.
I think of bloodworms as basically axie protein shakes, sure they will give him some energy and bulk him up, but a diet of them alone can leave em lethargic and in some instances constipated.