General rule of thumb that I use and I have seen others use as well. Take your height in cm and multiply it by .92
So I am right around 182 cm which means I ski a 167.5 pole. I tend to like a little taller pole so there is a little bit of personal preference to it but I would say if you are around 2-3 cm of the number you come up with you should be in a good position. I would start on the higher end of the range and see how they feel because you can always cut shorter.
Hope this helps and good luck with training going forward.
CXC Team Head Coach