FYI, 9-speed Ultegra shifters will work with either a double or a triple crankset. 10-speed Ultegra shifters are specific to either double or triple, although a 10-speed triple shifter would probably work with a double crankset, but not the other way around.

The best time to upgrade to 10-speed is when the old shifters are totally worn out because the shifters are the most expensive and most difficult to replace.

You may find that the old 9-speed shifters will work fine if you flush them out with WD40 and replace the cables and cable housings.

Al