New brass can have some defects in it. Such as uncut primer pockets, uncut flash holes, crap in the case, burs, or in my case, I had 50 S&W 500 shells that weren't cut square from the factory so I had to trim them all pretty low to get them squared up.
In general, I'd say FL size them, trim them all to the same size, check for burs and defects, then load them up. Others will go through a much more demanding process, but they are also probably doing a lot more than I am. I usually just punch paper at 100 yards max. But it all depends on what you're doing, going on a big game hunt, or shooting at 1500 yards, you're going to want to make sure every aspect of every piece of brass is the same, but for me, I'm doing neither of those so my process is less demanding.
After you fire them once you can just neck size to help improve the life of the brass.