If you are talking about the timeline on the ordering status page, I am pretty sure it is based off the most up to date information they have available. But it will change, pending on all the factors that can affect assembly and shipping.   I have placed 3 orders in the past 10 months, 2 Alienware systems and 1 G laptop system, and shipping times were acceptable and within roughly 3 weeks.
So I been looking at the forums and post that people make about the delayed orders for their products and it got me wondering how dell can promise the product will be built and shipped by the purposed date.
How does dell promise the “shipping” and “delivery” dates?