We usually go up to Ballards around Christmas time. By then they usually have about 16-24" ice. They start putting houses out about mid December and move with the fish. By Christmas time you are usually fishing about 26-32 feet water. This is all dependent on mother nature. We had some years where there was still too much open water for us. But, usually third week of December its should be in full swing. They use lighter transportation if needed.
Can't recommend those guys enough. The guides are top notch and the facilities are fantastic.