well, you can grow autoflowers completely under 12/12 (albeit with lessened yield), so wouldn't that mean that they should immediately start flowering once they come out if that did induce flowering with them? ;)
Those guys seem to back up my theory: https://2fast4buds.com/news/How-long-do-Autoflowers-take-from-seed-to-harvest
To copy:
"Autos – like regular plants – also spend some time growing in the vegetative stage. With regular plants, you can force them to flower by changing the light schedule. For instance, if you’re providing an 18/6 light/dark cycle now, you can make the plants flower by switching to a 12/12 cycle.
With autos, however, you can’t do that. Why? Well, it’s because autos follow a fixed timing. As soon as the plant grows for a while, the plant switches to the flowering phase on its own without your interference."