Joshua Norton's Proclamation of 17 September 1859 declaring himself "Emperor of these United States" would appear to settle the question of when Emperor Norton’s reign was inaugurated.

Except.

Except for a line that Emperor Norton attaches to his signature to several of his Proclamations of the 1860s, in which the Emperor specifies that a given Proclamation was issued “in the [X]th year of our reign.”

Assuming, for example, that a Proclamation that Emperor Norton signed “in the 16th year of our reign” was one he issued between the 15th and 16th anniversaries of his reign…

The “math” that the Emperor uses in these little clauses strongly suggests that he may have thought of himself as being Emperor for at least 4 years — and for as much as 7 years — before he declared it publicly in 1859.