Used to be that you could set raid cutoffs as to when you could start signing up and when sign ups finished.

I can't find that feature anymore - can you point me to it? wulfpack.dkpsystem.com

That's still there.

Admin > Schedule > Event Schedule.

Recurring events go in the form of "Days before raid to stop/start signups" and can be entered as a decimal (ie .25 = 6 hours).

For non-recurring events, you set it as a hard time by date and time.