vidmaster achievement on Halo 3?

[Mr. Bordom]

To get the achievement 7 on 7 do u need to already have 7 exp. when u play on the 7th? Or can u reach 7 exp. on the 7th and still get it?
Phil P. I'm talkin about the new achievements that just came out.

 

[Andrew S]

you can get 7 exp on the seventh day, so just dont play a certain playlist then when the 7th comes play hardcore and win 7 games, but its only 0 gamer score :S