600 and 600 sounds good, but after a while, instead of counting reps, go by time. 300 jelqs that take 15 minutes are just as good, if not better than 500 jelqs that take 15 minutes. Maybe go thirty minutes of jelqing AM, 30 minutes of jelqs PM. Remember to take a full three seconds per rep, feel the full expansion of the upper shaft/glans, and really concentrate and visualize the growth with each rep.