I’ve had bulk fermentation take as little as 8 hrs and as much as 16 hrs. It depends on your room and water temp (as well as flour type, starter strength and amount, and more).
I think it is best to look at the dough rather than the clock. When it is ready, there should be some bubbles/holes on the top, and if you use a clear container, look through the sides to see if some of the holes are close to the size of peas. I just took a pic of not-ready at 12hrs, and in about two hours, I’ll take a pic of ready, and then I’ll post both pics.
I don’t get much of a rise during the proofing stage. To know when that is done, I poke. If the hole barely rebounds, it’s time to preheat the oven.
I’m pretty new to this, so if someone disagrees with anything I’ve said, please speak up!