growing hawaiin skunk, need advise on when to turn to flower

[Revshot]

hey guys, i just got my clones ordered today so they should be here in a few weeks!

the strain is hawaiin skunk. my question is i would like to grow them to 2 1/2 feet total. i know these guys do stretch a bit once i put them into flowering, the question is how much?
how high should i grow the plants in the veg cycle before turning them into the bud cycle to obtain a total of 2.5 feet?

its a DWC set up under 3 400 watt mh's and hps's

 

[HB Rob]

I've got two Hawaiian Skunk at 49 days into flowering atm. Mine actually stretched very little. I'd recommend vegging to about 14 inches +/- 1 inch in order to keep things ~2.5 feet. Crop or tie things down as necessary.

 

[Revshot]

I've got two Hawaiian Skunk at 49 days into flowering atm. Mine actually stretched very little. I'd recommend vegging to about 14 inches +/- 1 inch in order to keep things ~2.5 feet. Crop or tie things down as necessary.

so its going to double in size? that seems like a lot of stretch?