I usually harvest when mostly cloudy - in soil, that's around 8-9 weeks, depending on pheno. I try and get them as bushy as possible before flowering, though that's easier said than done! But I get nearly three times stretch from inducing flower, but it's very steady, and predictable - no sudden surges...
Both my last two ended up around the 32 inches mark after flowering around 12 inches:
Both my last two ended up around the 32 inches mark after flowering around 12 inches: