On our QV Med. cruise in 2019, we booked a Q4 as soon as it went on sail. By the time, more than a year later that we sailed, we had seen the price more than double, then, in the few weeks before sailing, fall back slightly, but nowhere near the level we had booked at. Rarely have I seen prices fall to less than they were on the first day. This won’t help you much, but might when the next lot go on sail, which is often in September, so might be when you are on board.