I avoid culling ANYTHING until I flower them personally. I've ran test batches of seeds for breeders before, and its very interesting how much different plants can get once they go into flower. I always take a clone from seedlings, and then either flower the clone, or the original seed plant(usually the clone).
That way if I end up with unexpected males, I didn't cull the wrong plant, and if I end up with something special I find out, and don't miss out. I've had plants that seemed average in veg, but excelled in flower. Trying to get a clone off a flowering plant doesn't always work well, and re-vegging doesn't always work well.