Do you think its too late to keep the leaves smaller on mine? Should I go ahead and chop it now?
Venturing into the unknown is part of the fun of bonsai.
I've tried chopping my layer back and working it into smaller pots without much success - it does bloom though (kind of amusing having inflorescences larger than the plant
). Maybe I haven't pushed hard enough - I dunno and I'm donating it to the landscape in the next week or two. Its been 4 years of trying (not all of which were whole hearted).
I've got several in my yard and I am unable to tell if they are self-fertile or require pollen from another pieris to make seed. But, since you like them, you could get another one anyway (aka, 'just in case') and wait for one or both of them to make seed. Of course, you could just see if you can procure some seed instead.
Given the size of your plant, though, I would be thinking about trying to root a few cuttings and/or layering. That will be good experience that you may find to be lots of fun. Then you can experiment with those clones next year to see if you can reduce the leaf size significantly. Of course this will also reveal to you some of the effects of pruning/chopping, if you pay close attention, and you also could wire new growth to direct it where you want it to go. All in all that would be plenty to do while your new plant grows bigger/thicker over the next two or three years.
I'm not trying to convince you to make a career out of this one plant. I'm just telling you alternatives to 'chop it now' and hope it turns out to be a bonsai (not that there is anything wrong with that). It is your plant. It is your adventure.
Enjoy!