Flashbang : 25
Smoke Grenade : 9
(amxconst.inc)
If you wanna check it on a duration the better way to do is to use PreThink and PostThink (and honnestly I've never used it atm). But with one of these two functions you can check every frame of the player, and in this case, you just have to set a variable to 1 When the user starts.
Set it to 0 if : 5 seconds are reached or the player stopped his movement.