If I remember correctly, the "registration" is for three years. If you do not "introduce" by the end of the three years, the name goes back into the available pot for other hybridizers. If you really like a name but you have insuficient stock to support an immediate introduction, this gives you three years to build up your inventory while keeping the name.
For Blyth, the transition from the Southern hemisphere to the Northern can cause issues, so he seems to be taking advantage of the time delay. Sounds like "Sherbet Bomb" will be a 2016 introduction via Keith Keppel.
