How old!

For an autoflower like Dante's Inferno that just started showing pistils a week ago, you are looking at a typical flowering time of 8 to 10 weeks (roughly 55 to 70 days) from the exact moment it started throwing those pistols. * Weeks 1–3 (Stretch): The plant will keep growing taller and wider while building out its structure and pistil clusters. * Weeks 4–6 (Bulk): The pistils slow down their upward push, and the actual calyxes start stacking and swelling to pack on weight and frost. * Weeks 7–10 (Ripening): The white hairs start turning amber or brown, and you'll want to watch the trichomes under a jeweler's loupe to check for that cloudy/amber ratio before the final chop. Since it started flowering around mid-August, you'll likely be looking at a mid-to-late October finish depending on how heavy and dense the colas get.

definitely sounds like a photoperiod, but it doesn't matter now.. the only difference is the trigger to change from vegetative to flower phase. It's 'triggered' for sure either way.

Varies.. depending on your perception of "it started to get flower pistils" it is already in flower for at least 7-10 days. As with photoperiods, it's in flower before your eyes can recognize it. Unless you can resolve things at the cellular level, eagle-eyes :P If just preflowers, i'd assume you are already 7 days into flower... if beyond that and have buds forming tufts of hairs, it's probably 2 weeks into flower or more. Breeder estimates are hardly accurate, but better than a random guess.

That sounds more like a photo rather than a real auto, if it's been growing since May and is just now starting to flower. The original Dante's Inferno is photoperiod and has about 8-10 weeks of flowering. Do you remember which breeder the seeds were from?

If you germinated in May and it's starting to flower now, it's definitely a photoperiod. The average time for indicas is 6 to 9 weeks, while for sativas it's generally 10 weeks and more.

6-8 Weeks