For this Achievement you have to complete the daily bombing quests in 2 min 15 seconds.
What i do is ride over the area before accepting the quest to get everything loaded in the cache, then accept the quest and put the bomb in a convenient hotkey slot. abandon the quest. then when you are all and mounted up accept the quest again and head to the area.
the trick i use is that the bombs have a cooldown which make the timer really hard. but if you push the hotkey while its casting you can cast 2 bombs before it triggers the cooldown. when you do this it really gives you a nice cushion on the timer.
this works for both blades edge and the skyguard quest in skettis!
also for the winterveil achievment fa-la-la-la orgrila you can do the quest without the reindeer buff. you just have to use the reindeer on our mount right before turning the quest in. this helps alot if you only have a couple reindeer buffs and are afraid of getting knocked off the mount.