After sizing, whether you neck size or full length size.
Also, for many years I determined the overall length of the cartridge to rifling, using a 1/4" oak dowel and a sharp pencil. The Nosler manuals have the process in them. Basically, close the bolt on an empty chamber, insert the dowel in the muzzle and bottom against the bolt face. Make a reference mark on the dowel at the muzzle end. Then, open the bolt, drop a bullet (not a loaded round - the bare bullet) in the chamber and hold against the throat, using a pencil or similar. Insert your dowel again and make a second reference mark at the muzzle. Measure between the marks for your overall cartridge "jam length". Back off your desired jump and go from there. I'd suggest 0.030" jump for hunting rifles with cup n core bullets, or 0.050" for mono bullets (all copper) as a starting point. As noted above, this may be too long for your magazine - you will have to check.