YMMV, but I’d estimate anyone with more than 2,000 posts at the SDMB and at least 6 years (or however far back such records are kept, whichever is shorter) posting experience would qualify as a veteran poster.
My UWAG is fewer than 250.
Better definitions of “Veteran SDMB Poster” are warmly welcomed, as are other WAG’s and correct answers.
There were VERY few people around 6 years ago that are still here.
I’m pretty sure ** Lynn, Monty, Ed, Cecil ** and about a dozen others are from way back in the AOL board days.
You are not a veteran unless you’ve been blindfolded by masked men, drove into the desert, thrown out of the car, set on fire, and left for dead. Then when you wander back to civilization, you can claim the title.
I was in the U.S.A.F.
Does that count? 
Now unless you were posting from a C-47.
Yes, yes it does. With an upper case “V,” though.