Autos never match the breeders time. Tap root determines flower. The bigger the pot, the longer they veg. Bloom nutrients can initiate flower. Use veg nutes all the way through or at least til stretch is done.
Some autos won't show amber. With autos watch for them to fade yellow. Just watch your trics, pistils and calyx. When the pistils turn and start to recced the clayxes will swell.
Check calyxes trics not the ones on the leaves and check in several spots.
Its close. Another week to 10 days.
A good rule of thumb. If you think its done, wait a week.
You could also harvest buds in stages that way you get an idea of when you want to chop next time.