I think it really depends on the snake/age. The pink phase is the longest/hardest to recognize. The best thing to do is get them into sunlight, or some kind of natural light. The bulb in my snake room make them look pink before they actually are. I usually go by the dark pink when i'm measuring days, not a slight pink.
Mine also get really lazy when they go into a real dark pink. Usually 5-7 days they go into a blue phase, and about 3-4 days of that they will clear up, two days later they shed. I would have to go with 2 weeks for the whole process.
Of course, like i said, every snake is different. babies shed faster, as well as a snake that is hurt. The best thing i have ever done is get an iherp accout. www.iherp.com
It is really easy to track all of your animals. It's free too. I track weight, poops, eating schedules, and you can track a shed all the way from pink, to blue, to clear. It's really easy.