Seems different every year here. Ours begin May 1st, so about the last week of April I always ask to get paid out for any that have not been used. That annoys most of the sups, but that's ok with me.
Learn that lesson several years ago when they didn't pay off, and in mid June, I'd say, ask about it and they said that they were not paying automatically, so I asked to get paid out, and they paid out the current year days. Took a while to get that taken care of.