Ok, been doing research for Duet of Strings. According to Granny Smith in the Apple Family Reunion, Apple Family meets every 100 Moons for a reunion. But according to Applejack back in Season 1’s Applebuck Season, the Summer Sun Celebration fell on the last Reunion.
Usually, in our own time-keeping terms, one moon=one month.
100/12=8 Years, 4 months, IF they follow our Calendar.
Since this is a Duet, I've been doing a disfavor to my addition to the Apple Clan. As such, let's strike up the melody that accompanies the bass, hmmm?