Good Question, Bob
Have to say - I did think you might ask it, too!
You'll know more - as others will too
Flagship might even have it on record somewhere...
Don't you think the time would have to be / have been calculated from the very first sign of movement off the stocks, until the tip of the bulbous bow is also submerged?
Otherwise and less technically, from the crash of the non-bubbly wine, I s'pose
Do you think there would have been someone on the ground to witness and time it?
Hope that all's well with you -
and hoping too, that your desk is less airborne than you might be!
Rosie