I have another question that is quite germane:
Is it any good?
Have you tasted samples?
What type of wood?
If it is a bourbon cask or a refill sherry 14+ years will probably continue to mature nicely.
However if in a fresh sherry hogshead, you'll probably want to sample ASAP. I wouldn't leave it in a fresh sherry barrel for longer than 15, the sherry will really overpower the distiller character...if there is any!
I'm patiently waiting to be in your boots with my own cask...I hope you have at least sampled it once already!