Some people say it reduces growth. You can get whatever yield you want depending how long you are willing to veg. It is impossible to reduce potency unless you know how to alter genes at a DNA level. If you are worried about fastest growth, then take a cutting from the revegged plant and grow that instead of the revegged plant. It will be identical to the plant before it was revegged. Anyway I have not noticed that revegging reduces growth, but I've only done it 4 times on 2 varieties.

It's not so much the time but how big and strong the mother is before taking cuttings. If you are growing with a small CFL, then it may take 6 months before she is strong. If you are using a 1000W MH, then it might be ready in 4 weeks. It just depends on if you think she can survive cutting some shoots off.