Hoyden:
Everyone seems hung up on the word "advanced" in advanced open water - it really seems to be OW2 and if it was called that, no one would object to you taking it immediately after OW. After going through rescue, I think that basic dive instruction should include OW, AOW and Rescue - I understand the logic in breaking it down into separate classes (marketing, logistics, $$$), but I think that safety and the recreational value of diving would both be improved by having all new divers receive more comprehensive training.
Jackie
Jackie, you are actually right on target about a lot of things here. Before NAUI changed its course names to make them the same as everyone else's, the first Scuba course was called Open Water I (now known as Scuba Diver). The next course was Open Water II (now known as Advanced).
Normally, I do not encourage people to take every class right after completing another. However, the Advanced class is designed differently than most advanced training classes. It is designed to give newly certified divers a broadened experience while under the supervision of an instructor. This way, newly certified divers can try some navigation, night diving, etc. instead of learning it on their own. Besides, how do you know that you will like wreck diving without deciding to take it as a specialty (which can take a lot of time after which you find out you don't even like wreck diving) or experiment and possibly get injured?
The Advanced class is designed to give small introductions to the kinds of diving available in your locale, so that you can decide which you will want to learn more about by diving and taking additional training. So, in this case, I encourage people to continue with this class right after their Scuba Diver training.
If you become involved in a serious diving accident or incident, you cannot stop time and tell your buddy that you will go back and take rescue training in another year or two. So, I also believe in taking Rescue training right after completion of your initial Scuba certification.
I actually used to combine all three of these classes into one program for students wishing to receive this kind of education. After this, it is time to stop taking classes and go gain some diving experiences over time. If you want to take specialty training, get some basic experience and then come back for it. On the other hand, this three class combination training gives a well rounded background with rescue education before going out to slowly gain experience.