My family will be heading to Europe very late December 2018 or very early January 2019. Likely flying into Milan. When would be the best (cheapest) time to book flights? As soon as they're released in presumably January 2018? Or wait until the first available sale? Is there a general rule of thumb? If it makes any difference we would prefer to fly out of Venice. Would prefer to fly Qantas or Emirates I guess. Also would be looking at an internal flight from Milan to Munich - any best time to book that? Thanks in advance.