Best to do it on first try. I wiped at 1st try ...1%.. :/
I found that on my first try he summoned first set of adds when he was around 30%? On my next attempts they appeared just after fight started and then around 50% of his hp. Then he got into his clone mode and I even got 3rd set of adds. Was very annoying.
Pop all CDs at the start and burn him from behind. When adds spawn kill them asap and continue to attack his back. If done properly you will finish him before he starts making clones. Beware that your cooldowns wont reset after wipe.