Do you guys start counting from switch or from first sight of flower?
The old standard, for photos... if it's clone, or 42+ day old plant grown from seed, then breeders would start counting at the flip. And for any plant younger than 42 days old at the flip add +1 day for each day they are younger than 42 days old. And that will get you as close to the quoted finishing breeder times as possible. But, as I was always taught, bitches will be bitches, so they will be ready when they are ready. But I gauge my ready by looking at the lowest pistil on any branch, as that pistil was the first one made, and it will be be the last one to completely turn brown and recede almost all the way in when she is truly ready...
Examples....
Day of Flip / Day Counting Starts
42 / 0
21 / 21
35 / 7
etc...
One week to go... (solid brown hairs, finally receding inward)
two - three weeks to go.... (hair centers are browning, but are still translucent on their edges, and no receding)