Pheno hunting seeds with 2 week veg

Got a bunch of beans I'm gonna pop looking for some mothers. I run 1 plant per sq/ft in my room. I am wanting to flip my seed plants at 2 ish weeks from germination, so basically 12/12 from seed. Should I wait for the seeds to be 4-6 weeks old so the are "sexually mature". If I do run them that small will I get a good representation of the of the plants genetics/ the size I'm looking for (1x1) . Will I have any trouble grabbing a couple clones at say week 1 of flower on these seed plants/ will the clone have good vigour coming from such a young plant? I'm am gonna flip the rest of my room in 2-3 weeks... Any thoughts or experience much appreciated

I've always tried to veg them at least a month before flipping so they can sexually mature somewhat before we start messing with hormone levels by reducing light. But I've heard some people do 12/12 from the very beginning in solo cups to go through large numbers, then just reveg the keepers. I'm interested in this method because I've got a bunch of Gorilla Bubble, headbanger f2, and gifted testers that i want to sift through in a relatively small space. Hopefully others with experience will chime in.

Hey budsicles,
I moved this question over to Marijuana strains and breeding.
"Help looking for moms"
Theres a little more info going on over there. Based on your screen name it sounds like we run our rooms fairly similar.