This page explains how to make time move forward in FFTA2 using Lezaford's Hut or the Witch's Hut.
Sleep in a Hut
To make time move forward, you can sleep in Lezaford's hut in the Aldanna Range, or the Witch's Hut in Tramdine Fens, to make time pass quickly. Choose "Just a little" to sleep for 20 days, choose "Pretty tired" to sleep for 60 days, and choose "Exhausted" to sleep for 200 days.
The months go in the following order, and each month is 20 days long.