Question about Amazon Category Best Seller

Does anyone have a clue about the timeframe to hit bestseller status? Is it a week or weeks? My concern is a lot of family, friends, and folks on the mailing list have purchased the book this week. I wonder if sales will peak over a few days and not have consistency over weeks. I have been number 1 in two categories since my book was released a few days ago. Does anyone have any thoughts or strategy?