If you’d like to date your correspondence with the Thelemic date but haven’t mastered the hang of determining same, the U.S. Grand Lodge website features this handy table of conversions from Gregorian to Thelemic calendar:
And if you’d like to include astrological data, you’ll find the current astrological date/time at th bottom of this page:
Meanwhile Clay Fouts provides a service called Era Legis which makes this easy for website creators.
But we know that you’ve already mastered and internalized this data YEARS ago. But you can share this with newbies. ; )