well im know expert but id let it finish flowering at least . maybe early spring .

Isn 't that what they're supposed to be like anyway?
Looking forward to what others say.

Should be pruned back in Spring, before it flowers - it will then flower, but later. All you can do now is trim back longer growths, unless you sacrifice the flowers its got now and give it a good haircut. It'll probably produce more flowers later on if you do that, but might not.