Inexplicable as it seems to me, some people think an early start means meeting at 7 or 8 am and then driving a few hours to the trailhead. An early start means being on foot or ski some time between 4 and 5 am, depending on your trip objective. If you are really slow, you may have to start even earlier.
Working out what time to start is simple. Decide what time you want to be off the mountain and work backwards. Factors to consider when deciding what time you want to be off the mountain include, but are not limited to, afternoon thunderstorms, short daylight hours, slow parties, snow conditions, aspect, and rock fall hazard.
Today, Doug and I skied up Mount Brennan. We wanted to be off the summit no later than 10 am - both to avoid afternoon thunderstorms and to descend before the snow became dangerously soft. Allowing 5 hours to reach the top, we needed to start skiing at 5 am. In order to achieve this early start, we camped at the trailhead, were completely organized the night before, got up at 4.30 am, left by 5 am, and traveled at a steady and consistent pace. Our time estimate had been conservative - always a good idea - and we reached the summit in just over 4 hours. We were back at the truck just after 10.30 am, before the snow became not only dangerously soft, but poor quality for skiing, and well ahead of any daytime thunderstorm build-up.
Being able to plan a trip in this way is a very basic mountain skill that surprisingly few people possess. But, it ain't rocket science. Work out what hazards you'll be exposed to, figure out how to minimize them and take appropriate action. Simple really.
It's 9 am and Doug is perhaps 2 seconds from the summit