That will depend when it starts to flower and how you grow it.
growdiaries.com/seedbank/bulkseedbank/auto-og-kush
On average the others who have grown that stain from the same breeder have a harvest in 11 weeks or 2.5 months or 77 days. They grew it in soil.
The breeder says the plants will be ready anywhere between 56-77days.
Autos can sometimes flower early when there root zone becomes disturbed, this could be from transplant or over fertilization. As long as you do not transplant them and keep the feeds in check I would be aiming for 11weeks give or take 2weeks for margin or error.
Best Of Luck!