This is an old topic, but this is how I managed this in SketchUp 2017 Pro:

1. Download & install Jim's plugin from the link above.
2. Modify the file name format as you demand, in the plugin's preferences.
3. Re-assign Ctrl+S to the plugin's SaveAs command, in SketchUp's preferences.

Now you can save an old-version copy of your work by pressing Ctrl+S.

I needed this solution because I am exporting models from SketchUp to Unity3D, which only supports up to version 2015, whilst I am working in version 2017.

This is super easy of a workaround but I hope this made it clear for you )))