Shoulder it the way that I’ll be most common in the method you will be using.
I.E.
will you be mainly positional or prone
Will you be using a cheek or jaw weld (cheek for long periods behind the gun observing. Jaw for more dynamic shooting)
For me personally, I do mostly positional stuff, so I’ll set it on on a barricade (very stable though) and get square behind rifle. I use a jaw weld because I’m not resting the weight of my head as I won’t be on the gun for more than a few min.
So I get my head behind the optic as straight and square as possible and raise the cheek piece to the position I’ll have my jaw/cheek on it.
It will be slightly different feeling prone (I set my length of pull up for positional as well). But I only shoot prone to zero, true data, and the stages I’m forced to. So I can make it work more so than setting my rifle up for prone shooting and then making the other 80% of my shooting work around that.
If you’re mainly prone shooting, do the opposite.
Remember, resting the weight of your head on rifle is acceptable if you are going to be on the rifle for pretty long periods. The cost is your head pushing the stock down and away from your body (cause barrel to go high left on right handed shooter).
A jaw weld takes most of the weight of your head off rifle and leaves it on your neck/shoulders. This will influence the rifle less and produce less reticle wobble. The cost of this is a lot of fatigue if you are behind the rifle for long periods.