A couple random thoughts:
You have to live somewhere. Obviously we all want to buy low and sell high, but if you sell your house in an up market you just have to buy another house in an up market or pay someone else rent.
If you are moving from a smaller and cheaper home to a larger and more expensive home, the time to do so is in a down market. But, if you are downsizing from a larger home to something smaller and less expensive, the time to do so is in a seller's market when prices have risen.
If you have no intention of moving anytime soon, then it probably doesn't matter too much.