(1) First locate the campaign(s) you want to set up for ad scheduling. You will see a "New" word in red, that is the ad scheduling option, it looks like.
So even though I think I set my time zone, not once, but twice, I had to do it a third time.
(3) So here it is, my time zone is set.
(4) Then I proceeded to the Ad Scheduling page, this is what the basic ad scheduling page looks like at first sight.
(5) Then I clicked on edit next to a day and got this screen.
(6) Scheduling things up and then moved on to test out the "advanced mode" which looks like;
Click 'Edit' to set custom prices for ads on a given day and time. Example: If your default bid is $1.00 CPC, and your custom "% of bid" entry for Tuesdays is 120%, your CPC bid for Tuesdays only would be $1.20. When satisfied, click 'Save Changes' to activate Ad Scheduling.
That is it really. The Google AdWords help center has more details at what is ad scheduling?
Continued forum discussion at WebmasterWorld.