Is it worth it to clone from a plant that you dont know the sex of (random seeds)? Is there ever interest in clones like this or do people strictly want female clones? How might someone go about cloning from this type of plant at 4 weeks veg?
Some strains don't show sex while in veg at all, they require going to 12/12 for that (mind you, I haven't come across many). If I've got a strain that doesn't show, I'll cut clones off of each plant as early as possible, and throw the cuttings into my cloner. I'll then plant a single clone from each donor plant when they're rooted, and immediately put them under 12/12. I trash the extra clone cuttings. Labeling is important.
If a clone is male, I act accordingly. If I want to collect pollen from this particular strain/plant, I'll put the donor plant directly into flower (it's been a minimum of four weeks by this point). If I don't need males, I just trash the donor plant the male clone came from. If the clone is female, I'll continue vegging the donor for my prescribed length of time, possibly taking more clones, then go to flower.
Waiting is your easiest bet though, as like I said, most strains show sex while in veg. Somewhere between week three and five usually.