I would like to set the state to "Awaiting Change" when a Change is created from the incident using "Create Normal Change" or "Create Emergency Change" UI action.
When you create a change from either of those UI Actions, the Change Request field is populated with a reference to the one that was generated.
You can create a Business Rule for this that triggers when this happens. You can change the State once the Change Request field changes.
Name: Change Created
Table: Incident
When to run
Update: checked
Filter Conditions:
Actions
Set field values
Something like this