Adding an annotation to a multicategory timeseries trace

Hi all
I’ve got quite a specific issue.
I’ve got a multicategory plot where the xaxis is a timeseries and I need show whether the date is in the past or the future (status or outlook).
The annotation doesn’t seem to be able to understand the date in this scenario.
If I pass in a number for the annotation x value, then the correct value is labelled, but I need to be able to update this dynamically when the date changes from an external source.
Any ideas?
Here’s a simple example:
Thanks in advance.