Is there any calculation route for me to follow, some type time to start Decer the plane and the correct elevation for the distance in miles nalticas ???

You will find the answer here:

I am an accuracy nut, I like this the best it is what I fly by. It is intended for the A320 but there are things that you can use to apply to your everyday flying like how to calculate TOD = Top Of Decent. A simple way to calculate it is:
Use 6.5 miles per minute (at Mach .65 in descent) as the basis. If you are cruising at 33,000 ft. and wish to descend to 5,000 ft. at the next waypoint, at a descent rate of 1,800 ft./min., you need to figure the time to descend 28,000 ft. (33,000 - 5,000). …
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