Trimming trees time? When is the best time?

Pruning should be done in late winter or early spring before any growth emerges.

It depends on your climate! Here in Canada, they should be pruned just before first frost in the fall and after frost in the spring. So late October or early April.

i wouldn't top it. that will ruin the shape. talk to someone in a garden shop who is knowledgeable.

After leaves have fallen. Tree will not go into shock then.

very early spring before budding...or after the tree goes dormant...also look at he junction where branches meet the trunk....if you have a v at that junction...slide your hand down the branch and if you can't get your hand to the bottom of the v, cut that branch off...winter rain will create ice at this point and the branch may break off and tear the trunk....I love silver maple trees and found this out the hard way one winter