Hey Douglas,
While we have some fancy custom recurrence patterns that include specific “exclusions” in the next release, at present the only solution is unfortunately to use the “Break from Series” feature to, well, break that individual event out of the recurrence series.
Here’s a screenshot of the link to do this:

Once you do this, you can then adjust the dates of just that one specific event.
I hope this information helps โย let me know if it does and/or if you have anything else I can help with ๐
โ George