Autos usually go from seed to harvest in three months regardless of what you do to them. Light schedule, feeding, environment. I believe someone may have misled you. They will vary in size greatly depending on how you treat them but the time schedule is pretty solid.
You can put the light on a 12/12 timer and see if they will flower. Usually takes a week or two after you change the light schedule to see flowers or balls. If it does then you have a photo dependent strain. Good luck 👍 and happy growing!!!