Congratulations on your wedding!

Remembering back to my own wedding planning, I'm not sure. Reading online about how the scheduling works, as much as I understand it, it seems to be made in two-week 'blocks' that allow you to reschedule it to available times up to the cutoff period (the second Friday) of that block of time before your wedding.

As other weddings are also being scheduled in that time, it means that as you get closer to the originally chosen time for your wedding, there might not be much free times and days left by that stage, which might require you to wait til the new period has changed over. But it's rather confusing to me.

The best thing to do is check with the npc who handles the rescheduling at the Scantum of the Twelve and see what times that are left for you.

Either way, I am so sorry I couldn't be more helpful. Still, good luck with organizing your ceremony!