For each muscle group. Does it vary for you for each muscle group/lift? Do you time with accuracy? Do you gauge by your heart rate? Do you not bother (whenever you feel ready)?
Chest, Back, Legs, and Shoulders I stick to 2 minutes - Timed. Sometimes 2 1/2 for the big lifts like deads and squats.
Arms and calves 1 1/2 mins.