What Tigerman and String said. If you dive regularly or have an experienced buddy who can show you the ropes then AOW won't really teach you much so do it as soon as you get out of OW I think, if you plan on getting at all. I started off my AOW (mine took from March - Jun as I did SSI) with the idea I would learn a lot more about diving but by the end of the course I was only doing it to be allowed on charters to deeper dive sites, it doesn't give much benefit other than that to me. But I did have nearly 50 dives by the time I finished it... if I had done it all when I first started it would have been useful. Instead I went on charters and got instabuddies, not sure which way would have been the best to be honest... but doing it the way I did certainly made me realise how I need to be self-reliant, even when diving with a buddy!