Anybody?

You can cast it from start, but it will take quite some time to transmute large amounts of ore since your magicka won't be enough for more than one or two spells, and you then will have to wait for it to regenerate. With higher magicka, gear or potions to speed up the regeneration, and perks in Alteration, it will be quicker, of course.

I was thinking of casting after Out of Balance seeing how it regenerates your magicka so quickly, you might as well have unlimited magicka. However, I was wondering how much experience do you get, per Transmute Ore spell casted.

15 XP per transmute, and additional bonuses do not apply. It's one of the few scripted XP spells in the game.

At least, according to http://www.uesp.net/wiki/Skyrim:Transmute#Transmute