Hello and welcome. I don't grow this species and your climate is much different than mine so I'm afraid that I cannot give specific advice. I think I would hold off on any pruning for a while, little harm can come from a little 'growing time'
I know that there are bonsai clubs in your area that should be able to help. Being new to bonsai, a local club would be a good idea anyway.
Sorry I could not offer more.