At High Reaches, we play in real time. Each day in real life equals one day on Pern. That means weyrling training really does take a year and a half, and a pregnant character has to actually be pregnant for forty weeks.
For purposes of role-playing, each thread will take place on the day it is started, no matter how long it takes to finish, unless otherwise noted. Each thread should still have the date in the header (see the Calender for the exact date correlation).
While threads can be back-dated to a limited extent - a few days isn't a big deal, but we really discourage back-dating more than that, due to the real-time play - working forward beyond the current date is absolutely not allowed, as official events may take place.