Hey Brian,
I'd say break the "rules" as soon as you want to.As long as you are satisfied with your results who am i to argue.Have fun
.If you're interested in what others think of your trees post some pictures.If you don't care what others think of your trees...if bonsai to you is a medium of self expression,a hobby to give your hands something to do and nothing else then do whatever you want and enjoy yourself.
andy