The Signup Closes campaign date is aligned to Midnight, Australian Eastern Time Zone. The last time a fundraiser may create a supporter page within a campaign will be on the following day at:

7:00 AM Pacific Time Zone
8:00 AM Mountain Time Zone
9:00 AM Central Time Zone
10:00 AM Eastern Time Zone

For example, if the "Signup Closes" date is set to January 1st, the last date/time a fundraiser may create a page will be on January 2nd at 10:00AM Eastern.