When to switch to hps ? (pic inside)

[Artopex]

My plants are 5 days old now, they are about 2 inches high and I have used a cfl bulb since the beginning.
I have a 150 watt hps that I will use for the vegetative state and the flowering one.

After how many days can I put them in my grow tent and use my hps ?
some people told me to wait until they are 6 inches high.

thx for your advice.

 

[canabinerd]

Just wait until they have a couple sets of fan leaves, then gradually harden them off under the hps, put em under for a couple hours with your 150 12-16 inches above. Then double how long you leave them untill they are completely hardened. Then you can start lowering your light. I'm running mine about 8-10" from the canopy in flower.