I have explained it with a little more complexity than needed I think by calculating towards the FAF / FAP. After the FAF / FAP its a 3 degree path again anyway so to simplify it further you could calculate using total distance to go:
Altitude to lose / 1000 x 3 (3 nm per 1000 ft) + tail wind + deceleration. so with the example above:
FL350 to SL = 35 x 3 = 105 + tail wind (0) + deceleration (around 10 nm in level flight) = 115 nm.
The speed reduction from 290 kts or whatever you are flying above FL100 to 250 kts is not significant. Maybe add a few miles for that also, its not an exact science 
. If you want to fly a continous descent all the way down it becomes a little more complex to calculate.