It is not an easy drive to go up to Mount Bulla if you are not familiar with the roads there. You need to allow time to stop for toilet break, lunch, hire chain for the car, etc.
Also, if you really want to ski, I would suggest to spend at least 3 days 2 nights there. 2 day 1 night trip doesn't give you much time to do it, you need to hire the gears, etc, you won't have much time left to ski.