It's in veg when it pokes through.
There are a few variables to your questions.
What light(s) are you using?
What strain(s)?
How much seeds&room do you have?
Do you have patience?
How tall are they right now?
They are now just over four weeks old. I'm using a T-5, four foot, four tube light. Heat concerns in my closet with no air conditioning. I have a tower fan at one end and two four inch computer fans rated for ninety cubic feet a minute. One for intake one for exhaust in the ceiling.
I have nine plants in a closet 2 by 5 by 8. Four THC Bombs, two Caramelicious and three very good bagseed. I should be ok after the males show themselves and I thin them out. I'm keeping the males for pollen, seperate of course from the females.
The next biggest thing I have to look forward to in my life is dying. I've lived to become a senior citizen, I hope I have learned a bit about the art of patience.
I tried to fim six of the plants, ended up taking the tops out of three. I'm trying to keep them as compact as possible. I had one growing like wildfire so I figured it would be a male and really cut the top out. I won't sacrifice light to the rest of the plants for one. The two tallest are about a foot. They are also the sparsest, I'm figuring they are males. Who knows? The rest on average are about ten inches and I have two that have really stayed compact. One is about six inches the other about five.