When should I take protein shakes on rest days?

[Marwan]

Hi guys, I'm starting the rippetoe program thing posted here (thanks for bringing that to my attention, I'm excited), plus getting a good diet plan going and protein powder.. the rippetoe link has a good guide on when to take protein on workout days, but I was wondering if it matters when I take them on rest days? Or should I just get it in whenever during the course of the day? (ie is it better to take one right when I get up or go to sleep?)