I've been feeding occasional supers since day 1 when my cham was 3 mo. old.
I started with Small—not a problem. He's now 6 mo., has grown considerably, and I ordered some mediums (haven't arrived yet, and it's been a week). I'm not concerned about those either.
As for moving up to Large, I'm going to wait & see. My beardie scarfs down the Large ones like candy, but he's a bit bigger than a panther.