I wait until we have had a hard freeze and then cut my type 3's like Moonfleet back to one or two bud nodes per stem any time I have time before spring. I wouldn't prune yet as it is likely to encourage new growth now, not what you want this late in the season. Maybe someone who grows in pots in a zone similar to yours will add to this and tell you more specifically during the winter when to prune.

Thanks. So then do I understand correctly that by pruning after a hard freeze (which I guess means frost temps), that I won't run the risk of new growth...that new growth can only occur when temps are above frost?

And also....pruning during freezing temps...I guess that doesn't expose the freshly cut stem to any danger? I know that for many/most other plants, I thought I heard you should never prune in such cold temps...I guess because the fresh cut exposes the plant to the cold in a different way, which could kill the plant?

Hard freeze is not the same as a frost - hard freeze indicates several days below freezing. In my climate, I wait until after the first of the year before considering any pruning.......although we don't always get very cold weather, I am assured that the plants are fully dormant by that time and so unlikely to generate any growth than can be damaged by cold.

As I indicated in your other post, young/new clematis should be pruned hard their first couple of seasons regardless of pruning group. Moonfleet IS a group three so annual hard pruning - as nhbabs describes - is recommended on an ongoing basis.