Expect that they will at least double in height or more in the first 40% of the flowering cycle.

I flower 2 weeks after my clones root and things seem to be doing well.
If they were clones cut from a mature mother, then they will be at the same sexual maturity as the mom and can flower right away if you want.

Alternating nodes are a good sign if grown from seed.

There is an article somewhere on HighTimes that talks about 12/12 from seed.....search and if you really are interested, read.