taking protein powder is best used directly after your workout and right after you get up. why? quite simple actually. after your training you will need quick protein to start the muscle regeneration. after you get up, you will have used almost all of your protein when you slept ( also for muslce regeneration and growth). Because you want optimal muscle growth you will need to have acces to amino accids, protein. best way to get this is by taking protein shakes. so to answer the question, it is good to use protein powder every day after you get up. on training days it is also good to take it after the workout. BUT, take protein during the whole day, not from protein powder, but from milk, eggs, meat, chicken, turkey etc. your muscle will need protein all day! sorry for the crappy english, i tried my best. Hope you guys understand. Tom