This weakaura will show you when the crit buff is up and only the crit buff. It will also only show when your trinket is off cooldown. It will also show you the duration of your buff when you use it. It also will only load in combat.
My other versions of this weakaura for the other buffs.
https://wago.io/WfXsuuxFk -Versatility
https://wago.io/CK_-MeBoP - Mastery
https://wago.io/WfXsuuxFk - Haste