Sinterklaas actually starts sometime around mid-November, when he arrives from Spain by a steamboat called Pakjesboot 12. He always arrives on a Saturday, or to be more exact, the first Saturday after Saint Martin's day.
From the day he arrives onwards, children can put their shoe by the fireplace, chimney, or if you have neither, anywhere in the house will do. You sing some Sinterklaas songs, sometimes leave a carrot or some sugar cubes for Amigo, the horse of Sinterklaas. Then you go to bed, and the next morning a small present will be in your shoe.
My birthday is on December 1st, and back when I was still a kid, I always got to put my shoe in front of the fireplace on my birthday, up until Sinterklaas evening. Usually there was something edible in it the next morning.
The real feast is on Sinterklaas evening, the evening of December 5. Sinterklaas brings presents to everyone on that evening. It's all very exciting for a child! When there's nobody in the family that really believes in Sinterklaas anymore, it usually becomes a Secret Santa kind of thing, with names being drawn. You only buy presents for one person, and it's often accompanied by a poem about the person (or if you're desperate about the present).
After Sinterklaas has brought everyone their presents, he leaves again for Spain, not to be seen or heard from until the next year.
For more about Sinterklaas, read this article on Wikipedia, which is also where I got the pictures from. All pictures were free to use in the public domain under the Wikipedia Commons.