Yeah I always put the first hit on the beat.
Dunno if it's your case here but when I gotta program drums, I never put this kind of stuff exactly on the beat. I usually put one a little bit before the beat and the second one where it sounds the best. The same rule for the velocities.
I've also had a period messing around with flams and drummers (when listening back) often always "object" to it being first hit on the count because the second hit sounds late-ish.
I've had a Music Grad drummer (that now teaches overseas) tell me that it's 'supposed' to be one hit before the count and one hit after. Which theoretically makes sense because a flam is considered one beat hit twice so the center of the flam needs to be lined up with the grid (again in theory).
In practice I just sway the flam back and forth while listening to the rest of the drum beat and see if the rhythm swings correctly.
Unless of course the flam is an accent at the end of a passage or supposed to be dead on with another musician stopping, then lining it up (aurally) is better.
Because I'd imagine you want the tail of the last hit to end with the tail of the rest of the music and not have the second snare happening fractions after the rest in the composition has already hinted at stopping.
I've had a Music Grad drummer (that now teaches overseas) tell me that it's 'supposed' to be one hit before the count and one hit after. Which theoretically makes sense because a flam is considered one beat hit twice so the center of the flam needs to be lined up with the grid (again in theory).
That ^ OR.. Technicaly.. if your playing 8th notes and you add a flam on beats 1 and 3. (ex : Flam + 2 + Flam + 4 + ) playing the first hit of the flam on the beat would be like your playing sloppy 8th notes!
I dont have the link right now since the PC at work sucks hard.. but look out for the 40 basic rudiments of drumming on the vic firth sticks web site! It's pretty clear that the flams or drag are added in FRONT of the patterns! As a drummer myslef I always edit/play them with the accent on the beat.