My husband always gets frustrated when he hears someone announce the first annual event. “How can it be first annual if there has never been one before?”
Inaugural – Marking the beginning of an institution, activity, or period of office. A formal Beginning.
Annual – Occurring once every year.
With these definitions, it is not possible to have a first annual if it has not occurred in previous years. Stating something is the inaugural event means it is the first ever, but with hopes that it will continue into future years. Then if the event does not happen the next year, it would not have been annual.
Also, what if you plan an event with no intention of continuing into previous years, but the event is such a success that it demands another? It could also turn into a semi-annual or seasonally. First Annual is sometimes rejected by newspaper editors because it's predictive and doesn't describe the present state of affairs which reporters should report. You could say 'first of a planned series of annual' but until the event has occurred twice it isn't actually being held annually.
When you are born, it is known as your birth, but you do not get a first birthday until you turn one year. You cannot have a first annual birthday on the day you were born.
There is no such thing as first annual if it is the first time for an event. It is pretentious to state an event is the first annual and many editors will not run press releases if that are stated as such.