It takes about 2 weeks for me to recover to 98%. The remaining 2% takes a month to get back.
I don't feel any serious POIS effects until about day 2-3. Then I can tell when my voice changes.
I've found that zinc supplements, as high as 250mg in a day, along with omega 3 supplements helps recovery. Eating fresh sushi also helps, probably because of the high levels of fish oils. But it doesn't reduce the recovery significantly. Maybe just 3 days. Eating these before POIS can stave off the intensity of the symptoms. Personally, I think my body's testosterone levels or the use of it drops sharply.