Sag measurement question

I bounce up and down on my bike first to allow the shock to settle, and then I have someone measure from the rear axle bolt to a specific spot on the rear fender. Ive never "warmed up" my shock though...

Quick answer is no, you can set it in the pits called with no warm up. However that does not mean you can't reconfirm your settings once you've been in the track and warmed up

This is how I do it, too. Bounce up and down a few times.

You will get a slightly different sag number after riding a moto because the oil gets hot. Most people set it before the bike gets hot.

Measure from your swingarm pivot bolt to the rear axle, and then mark a spot under the seat the same distance from the pivot bolt.

Once you get your race sag set, be sure to check static sag (difference betweeen bike unloaded and resting on the ground under its own weight, without rider). If you don't have around an inch, youneed a stiffer spring. If you have more than about an inch and a half to two, you need a softer spring.

The Race Tech method works well.
Have the rider stand on the pegs rather than sit down. This is for consistency.
Lift the rear of the bike @25mm, then let it lower slowly until it stops. Measure the sag from the rear axle to a point on the fender directly above.
Push the rear of the bike down about an inch then let it rise slowly until it stops. Measure the same as above.
Average the 2 measurements.
Then measure with the suspension fully extended (on the stand).
Subtract the average measurement from the fully extended measurement. This is your sag.
Then measure static sag as described above.