Valerian acts on GABA A recptors so is unlikely to be helpful in allowing the receptors to regain their sensitivity. Individual effects vary wildly so no-one can tell you how long it would set you back.
Adding back another GABA agonist like valerian, when you are completely bz free may well confuse the receptors whereas using it at the end of a taper may be less of a problem.
The prevailing wisdom is that receptors will recover best if left alone. Theanine would be a safer choice as although it has a modulatory effect on GABA, it does not appear to act directly on receptors.
There is some limited evidence that rhodiola can help with mental fatigue. It is not known to have any safety concerns & has no known interaction with GABA.