With most factory ammo, there's a ballistic table available for each caliber based on the numbers found on the box.
For myself, I boresight first.
Then, I figure out what I want my zero to be (100, 200, 250, 300, etc.), and reference the tables to find out where the ballistic parabola intersects line of sight on the upswing.
For example, for my 308WIN, I wanted a zero of 300 yards. Per the tables, it shows 17 yards (50.5 feet) as the point of intersect on the upswing, 300 yards point of impact on the down.
So, I set the bench up at 17 yards, take 3 shots, and adjust in the extreme (I usually go a little past where I think the adjustments need to be), and take 3 more from the bench. I make my final adjustments, and take 3 more, verifying my zero.
Then I take it out to the full zero range (300 in this particular case), and take 3 shots.
I make any fine adjustments needed to dial it in just right, then take 3 more to verify.
If I need to adjust any more, I still have 5 rounds to make it happen, or I can just continue the range time as I see fit.
I do my best to get as much trigger time as I can muster and pay for the ammo to boot.
IMHO, one can never have too much trigger time...
I also pack my prized rifles in hard cases with extra padding, just as added protection. They don't get tossed around by gorillas, and keeping them "armored" is just peace of mind. I have yet to have a rifle get knocked off zero using my methodologies, including multiple segment flights cross country.
An ounce of prevention....