topping plumies

When should I top my plumies to get them to branch. Mine are 2 years old and from 18 to 24 inches tall. Most are ready for repotting but thought I would wait till spring. What I need to know is should I top and plant the cuttings now or wait till spring? Where should I cut and should I wait till they are callused over before planting the cuttings?

OK, we need more info.
Are these seedlings that have never bloomed?
Generally you don't 'top' plumeria to get them to branch, they will branch naturally when they bloom.
In any case, spring is the best time to take cuttings.
Can you show some pictures?

they are seedlings that have never bloomed. Will they branch out if you top them?

They probably will. However, you will slow their first bloom cycle, in all likelihood.

Then I will let them bloom and then cut a couple to see if I get what I am after. Which is more of bush with many branches. What tool is best to cut them with a saw or pruning shears?

A sharp knife is what I prefer.

A alcohol disinfected sharp knife.