Very simple VWP question - help appreciate

[DThompsin]

Hi,
my question is I am going to visit friends in the US next month, and Im using the VWP, now I'm going for 2-4 weeks, and Im not sure exactly how long, but it is under the 90 days allowed. I dont know how long to book a flight as I wondered if they will stamp my passport for 90 days, or will they stamp it based on the return date of my flight? As I may need to alter my flight while there and dont want it to affect my status. Help very much appreciated. Thanks.

[PraetorianXI]

You need to book your flight right? so just book it for your planned stay. The I-94W will most likely be given for 90 days...