Descending with a large heavy jet simply does not take the planning associated with an Apollo moon mission, yet I have watched First Officers over the years start deciding when/how to descend when they were at TOC.
The usual 3xaltitude+10 works nearly every time.
So, at FL350 it would be 35x3+10....descent 115 miles from destination.
Headwind?
Eliminate the +10.
Tailwind?
Add another +10.
This worked very well in the heavy jets I've flown over the years...even the B707, long ago.
In the end of course, it's ATC that will do the 'deciding'.
