Since you have match brass, it's an excellent bet they were not fired in a machine gun, so I'd suggest checking the case length before you trim. It's possible they may be within specs without any trimming at all. Just a suggestion. (BTW I hate trimming, can you tell?)
If you do trim, I'd recommend 1.990 length. I trim to this length, reload 5 times, and pitch the brass. Never have to trim it again. I shoot it in an M1A, an M14, or a FAL so I use it pretty hard.