It depends on the garland. I have a garland of little wrapped presents that I like to put on after the lights but before the ornaments. If it is the fuzzy tinsel kind, I like that last so it drapes nicely on the ends of the boughs.
Who still puts tinsel on their tree? I stopped once we got an artificial trees because it is a pain to take it all off before storing the tree. Do they even still make tinsel?