Well, I have limited experience with Autos. I have only grown one variety to harvest (5 times), and my fifth grow is nearing completion. I think that for those that like to count, the clock starts when they break soil (medium). But I don’t count days anymore, because they’re ready when they’re ready, regardless. I started my current Auto grow around June 1 or thereabout, and they only need a few more days ‘till harvest.
Good luck finishing yours up smoothly.