A Royal Sovereign pre-dreadnought at Trafalgar

What if a Royal Sovereign-class pre-dreadnought appeared at Trafalgar, and how quickly would Nelson take command?

Its six-inch guns are expected to devastate the opposing sailing ships; the command-transfer timing is not answered.

The question introduces a Royal Sovereign-class pre-dreadnought into Trafalgar and asks both about Nelson taking command and the damage it could do. The reply focuses on its six-inch guns. Those weapons are expected to have a decisive effect on the French and Spanish sailing ships. No separate timing is given for the proposed transfer of command.