Make your own time chart, but be careful
Those without charts giving time to V1 / 100 kt./ 90 kt. can begin charting the weight, derate etc. against time taken on the stopwatch -- and start checking the airspeed when that time comes up.
Be careful about using the time measured at MTOW with derate when you're light as you will likely be much farther along the runway when that time comes up.