To celebrate the day, how about attending Alere Flammas's Sorting Feast?
The Hogwarts Express arrives at 8pm Eastern and the feast begins at 9:15. The earlier you arrive, the more fun can be had.
If you haven't created a character yet and intend to:
Do it ASAP! Especially if it's a first year character. We need time to approve your application and prepare for your inclusion in the Sorting.
If you have a student character already:
Show up as early as you want, there will likely be train rp before the train actually arrives. If you can't make it for 8pm, show up when you can, you won't have missed everything.
If you just want to watch:
Log in whenever you like, using 'connect guest guest', and then '+watch/on hogwarts-gh' to watch the Sorting from afar. That +watch only shows the activity in the Great Hall. If there's enough interest, we can add another room or two so you can watch more of the action. But the trip to the castle does involve moving, so the only way to see everything in every room is to.. make a character! :) (Or read the log later.)
Come for the Sorting Hat's song, stay for the Headmaster's longwinded speech.
Hope to see you there!