Just figure 2 minutes per question and use that to gauge. Adjust for the number of questions for Q and V then find what you're comfortable with. I personally like 5 questions x 2 minutes. So every 5 questions I would check to see where I was at. On question 5, I should be at about 65 minutes on the clock. On question 10, I should be on about 55 minutes. On question 20, 40 minutes should have gone by so there should be 35 minutes left.

This method was easier for me because I could always check at any given point instead of using specific time yardsticks.