you have regular autoflower seed? that's unusual. home brew? if so crossing with a photo male will not produce 100% auto seeds.
proflowers will show when they show.. probabl 2-3 weeks from sprout? unless it's some long-lived XXL autoflwoer strain, then you wait longer.
you see preflowers about 5-7 days after the plant switched into bloom phase. with autos, you have no idea except in hindsight from visible preflowers.