With the recent release of Google Cloud Scheduler to beta, we’ve published a step-by-step tutorial on using Cloud Scheduler to schedule start/stop of GCE VM instances. Please take a look!
In parallel, we’re also looking into ways to make scheduling VM operations even easier.
This is something we are planning to improve, hopefully later in the year.Carl Smith commented
Understanding that editing an Instance Template (IT) that is in use could lead to problems with mixed instances in the same group, however, editing an IT that is not in use on an Instance Group would make things a lot easier to make a tiny change.
Especially when the "Copy Template" does not always copy ALL of the settings across to the new template. I have had things like "Delete Disk" and metadata not copy across to the new template (even just now).