I use an even better technique. I just arbitrarily select an arrival time and push the nose down till the ETA on my wrist GPS says the same time. Of course you have to have the GPS set to read in 24 hour time mode, or you could be out by twelve hours
Actually I like to be at overfly height a few minutes early with everything put away, fly zipped up, ERSA read, frequencies set, ATIS, etc.so that all I have to do is think about traffic, joining, landing checks and how I'm going to go around if I stuff it up and brief any passengers accordingly. 500 feet per minute in a cruise descent seems to work.