No harm in waiting a while to see if they get more vigor as the grow. I am sure others may do it differently however, I usually cull out the weak ones fairly early say when they get their third or fourth set of leaves. If they are not vigorous at a certain point they are probably a phenotype you don't want to waste time and energy on. I sort and label each plant and watch it mature and before I flip them I clone a bunch out of the ones that show the most vigor. Then I continue to watch the grow recover from the clone cutting and move into flower. In the end when I weigh the output of each plant I decide which clones I want to keep and toss the rest. That way the next run I will have a mother plant set aside and clones that are the most productive for the next run and into the future. My goal is to find the one phenotype in the seedlings that has the best performance. Sometimes I might find 2 I like based on different qualities but I am really looking for one so each grow is consistent in how the plant responds to nutrients and the environmental conditions.
Dee
