Lower leaves seldom recover and the the plant uses what it now has to build new stuff. Don;t cut the leaves off. The plant will drop them when they are no longer usefull.
On the flower switch, I wait until the plant starts growing alternating leaves (leaves do not grow right across from each other) to make sure it is mature. If you have the time you will increase your yield by letting the plant mature. Another factor is available grow height. Expect your plant to triple in size at most ( but it's possible depending on the strain). It will most surely double it's veg height. If you have height restriction, use this info for planning.