When does flowering timing wise start?

I keep hearing different times to start calling it the flowering cycle....

1) When you turn on the 12/12 cycle.

2) When the first sign of flowering happens usually about a week to 10 days from 12/12 start.

What is correct for an 8-10 week flowering plant?

Flowering starts when pistils form. Switching to 12/12 just means you're inducing flowering. I usually start seeing hairs in less than a week after switching to 12/12.