I think you need to consider what it is that you're trying to measure. If you record the total time to make multiple cycles you will determine the average cycle time more accurately than if you time just one cycle. Bit if your goal is to get the most accurate representation of the time for teh first cycle only this won't help. You're better off measuring the first cycle many times over, then determining the uncertainty due random variation. You can also get an estimate for systemic variation by using your timing mechanism on a well-known, calibrated system - this will tell you whether your measurements are consistently high or low.