My 2 Cents...
You will not outgrow the 16kg bells.
Of course, it depends on your goals. Are you trying to work up to high rep numbers with timed sets, i.e. 150+ snatches, 80 Jerks, ect ect? If so, then start light with a 16kg bell.
I always use lighter bells. I may do 15+ minute sets with my 12s. 16s are my working weight for 10 min sets, and I do timed work with 24s. Of course, KB lifting is my primary modality.
The 16kg won't be too light provided you have high rep aspirations...at least not for a long time. If you don't want to do high reps, then go to a 20 or 24kg..or find someone local that will let you try theirs to get an idea.