Most of my Satsuki Azaleas are starters, obviously. Some are 12 to 15 years (they will be published as they bloom). It will take double that time at least, to shape them into bonsai. If you are interested to witness their progress, then you might like to follow their journey here.
Where possible, each Satsuki species description is linked to the Azalea Database to facilitate verification and additional information of interest. And then there is the Satsuki Azalea Care Guide.