Do your best to get the same instructor throughout your training:
The continuity avoids the 'three steps forward one step back' effect as each new instructor tries to catch up with what you've done already with previous instructors.
It will save you money in the long run..
(At the same time, however, don't be afraid to change instructors if you don't hit it off with one)
Good luck and enjoy your training: it's a very rewarding time, not always plain sailing but the end result is well worth the effort.
Cusco