Hi Dave,
I don't know if this will help, but we went to Florence on Easter Sunday this year to see the Scoppio del Carro ("Explosion of the Cart"). As you would expect it was absolutely heaving...
The queue for the Uffizi gallery was taking over one and a half hours for those who already had booked their tickets online and about twice as long if you had not!
It is really worth going to but be prepared for possibly a long wait.
Hope you enjoy it - John