How long that it take to travel to lake lugu from Lijiang? How is the road condition there in Dec?

Long-distance buses at LJ Bus Station can take you to the lake directly.
The schedules are 08:00, 08:10 and 08:30. It takes around 5 hours on the way. And the ticket fare is CNY 96 to CNY 100 per person.
In December, it perhaps snow at that time, which will make the road condition rather bad and some buses may stop running. So you'd better check the schedule again before you start off.