I ran my auto's 24hr on, for about the first week, then flipped directly to 18\6, then actually back up a little to 19\5 (I had my side lighting on 18\6 but my main light on 19\5.. I was trying to mimic dawn\dusk a little - tip - don't bother).
Whatever you have an auto on it'll use, however 12/12 is likely to reduce your yield but they'll grow on schedule pretty much no matter what lighting you throw at them, I do suggest not going 24\0 though, a little break of even 3-4hours can be quite helpful for the plant.
On the over watering a tad... don't sweat it, most important is that you were aware of it and not doing it repeatedly.