To advanced open water, or to not advanced open water. This is a debate I have seen go back and forth over the years, and it seems like people get hung up on the word advanced. I would not consider AOW advanced in anyway, I think a better name is OW 2. I will say I took AOW right after OW. I will also say my instructor sucked, but I didn't know what I didn't know. So a top notch instructor may make the experience more "advanced", I don't know.
To me in OW I learned how to get comfortable in the water, how to breathe, how to use my gear, and how to complete a dive without getting hurt. If you are comfortable in the water, and are comfortable with those basic skills, the AOW just goes next. it taught me how to "do things" on a dive, like navigate, dive at night, and dive a bit deeper. But I can't say there was anything advanced about it. just the next iteration in dive training.
So when to take it? After you have had enough practice to feel comfortable with the basics, and when you feel it is time to move on. (everyone is different)