Use your ETA to destination, “ETE to Dest”.
First off you will need a flight plan so you know time “ETE to destination”.
If you are cruising at 20, 000 ft, you can start your descent 20 minutes before “ETE to Dest” descending at - 1,000 VS,
10 minutes before “ETE to Dest” descending at - 2,000 VS.
You will always come in early and will have to reduce your VS as your aircraft slows. Which is what you want, since you never want to come in to high.
I use it all the time between waypoints as well.
Here is an example;
When I am cruising at 20,000 ft towards KPDX, I know I have to be above 12,000ft when crossing waypoint KRATR and I have to be at exactly 5,000 ft Max 210kts at LIQWD.
Therefore four minutes - 04:03- before KRATR I start descending at - 2000 VS to lose 8,000ft (screenshot).
(As you can see in the first screenshot, “ETE to Dest” is also 10 minutes (10:38) so starting descent at - 2000 VS will get you there as well. Of course it will take longer to arrive because as the descend your speed and VS will decrease as well.)
On my way to LIQWD, I continue at - 2000. As I get closer to the waypoint I am reducing my speed to below 210kts so my vertical speed will reduce as well. Just keep an eye on your “ETE to Next” to adjust VS accordingly. By the time I arrive at LIQWD I am usually around - 1,000 VS.