What height do you start flowering?

How does that work out for you?? What lights you have on them?

I use 400 Watt HPS...

it works out great! about 1.2 o's per plant

All depends on how your growing.soil aero hydro,scrog,sog, seeds,clones.I like to veg 10 days for aero which gets me to about 14 inches then finish around 3 feet tall.Soil I veg for about 3-4 weeks to about 14 inches then go 12.It all depends on your wants needs and abilities.Use your height but dont underestimate the flower growth

It all depends on how much space you have to work with. check out my cabinet grow.
Lowrider # 2 grow journal first time grow
i am using a 400w light one plant
please comment

yes, yes, yes - agree with the folks saying it depends on how much space. my most recent grow has tripled in size since switching to 12/12.

for my first grow i vegged them until 15 inches and ended up with really nice 4-5 foot plants. yeilded over 3 ounces each plant. i am scroggin now and from the looks of the stems crawling the screen i would say my plants are over 2 feet tall and im still vegging. it just all depends on your situation like Fletch said. theres no set time limit or size which u flower at. it just all depends on your method, grow area, time, etc.

my plants about 6 inches can i flower it? its been veging 6 weeks

im at 4-5 inches....
going to switch to 12/12 at abt 8-9 inches....
plants should top off at abt 4-5 feet.... but it all depends on the strain