I know sometimes [before i got my timer] i would let the light go over a couple hours, like 9 at most and my buds still turned out good, 19 is bit more lol, but if your only 9 days into flowering [im no expert] but id say as long as it was only once it shouldnt do to much damage if any...I mean if you continuously let it go like that it would be forced back into veg, just make sure you got the timer fixed and everything should be fine. As for flowering duration, it depends on the type and potency you want but id guesstimate 9 weeks give or take