Some say yes and some say no way. I'd like to see younger females at least 60+ grams before they ovulate, but you're still dealing with mother nature and can't always control when a female ovulates. You have to still make sure she's in good breeding health first, not just because she's ovulating. Setup has to be right, she's getting everything that she needs in way of calcium and vitamins, etc. Younger females can have complications that mature females wouldn't normally have. You run a risk any time your breed, any animal at any age.
I don't breed untill 60 grams but I just received Urban Geckos newletter and they say they breed some of their geckos at 45-50 grams. But I'd say most people on here would say wait untill they are heavier.