You might have to go in person and make an appointment. There's only a one-week window to make appointments via the Apple website or AppleCare phone support, but there's a longer window of available appointments if you go in person.
I went to an Apple Store yesterday and I actually tried making an appointment using one of their computers. Then when I asked an employee I was directed to the Genius Bar gatekeeper. He showed me the available appointment slots, which was for maybe 2 weeks. 8 days later was already pretty full, and those weren't even available to be booked online or over the phone. However, there was an available slot later in the day.
Of course I'm guessing this is probably a special trip for you? If making two trips is a problem, then yes you're probably going to need to wait until midnight.
Judging by your user name, are you Dinuba, California? I'm showing that the Apple Store in Fresno has Genius Bar appointments this Friday to Tuesday. There's also an Apple Authorized Service Provider that has appointments today. The latter might not provide free diagnostics like they will at an Apple Store, but if you have a legitimate warranty issue the diagnostic should be free.