When i started to jelq last year i did it for 7 months (3hs per night) i gained 1.8" lenght but i get thrombosis so be careful dont overdoit , jelquing is the most underrated exercise in my opinion. If you like fast strokes i recommend 50 and if you do them slow 100 strokes , use much lube as u can to avoid injury and trust me i used to think that 50-100 jelqs were nothing.