That does seem a little too fast. But then again I've never had an auto male.
Read through my Short Stuff Onyx Auto grow. He was confirmed male at day #19. Six days later I started collecting pollen and by day #38 I chopped him down after collecting .5ml of pollen. He was almost 16 inches tall when he got the blade!
https://www.autoflower.org/f44/1st-...delicious-northern-lights-blue-fem-19340.html