Please see the underlined text and then the bolded word.
If you are tired of waiting, all you can do is reset your game and start a new Pokemon Dream World account and never touch your clock or calendar ever again. If not, then you have to wait until you can access it. There are no other answers. Those are your only options.
I believe you have to leave your DS off for the entire duration as well. I had that issue with my original black when I reset my time for DLS and it took a week of not playing it for me to get access again. I asked Nintendo directly for help and they said, to wait 24 hours just as it says in the manual.
You also have to save your game AFTER you changed the time. If you never saved, then that is a reason its not resetting.