I don't know if there's a template, but for my timeline I made a table in Word and made a vertical row for each major arc of the story on the far left, and then horizontal columns--one for each major plot, subplot, or theme--along the top right. Then I just wrote in all the important events that occur to develop each of the subplots or themes during each arc.

In my outline/list of scenes, I also chose different font colors for subplots. It helps to keep things clear in my mind.

This is just my way of doing things, though. I hope it can be of some help!