Earliest Known Use?

Revenue stamps were introduced for use on 1st January 1867, however it appears that some were released earlier as the above image clearly shows the date 17/12/1866.

It is unlikely this date was written in error as presumably the new year would well and truly be entrenched in the clerk’s minds some 11 months later!

Can anyone improve on this date?

The above image was supplied courtesy of the collection of Walter Gill