Four adjustments make winter work rather than merely be possible. Warmth, somewhere room temperature or a bit above and away from the cold window, and a seedling heat mat under the jar speeds it up noticeably. Light, as bright and indirect as you can manage, and a small grow light earns its money in a north-facing flat.
Then less water than summer in soil, and patience: do not lift the cuttings every few days to look. Firm base and healthy leaf means it is still working.