I am at the stage where I am not sure if i am vegging or still in seedlings stage with my 3 part GH.

At what point are your plants not seedlings and are ready for the (1/2) recomended amount for veg, and out of the seedling cycle.

So I guess i want to know how many sets of leaves do you need to not be a seedling anymore?

Most people start at anywhere from the 3rd to 5th node. You should also start if you notice deficiencies forming in the leaves or if the cotyledons yellow and shrivel. Start at a 1/4 strength solution for the first week, 1/2 the week after, then full strength. You want to slowly introduce your plants to the nutrients so as to avoid stress.

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Blue Apollo - Flowering

AK-99 - Flowering