I sent 6 guitars in a moving van across the US...it worked well. Put the cases in the cardboard clothing wardrobes.
I only sold one guitar before the move, so i cant give you much input based on experience. I can say that the amount of time it takes to sell a guitar has a lot to do with whether it is a guitar that will appeal to a lot of folks: a commonly known maker (Martin and Taylor and Gibson for sure, maybe also Collings, H&D, Bougeois as well), using common woods (EIR and mahogany), offering a size that is popular (dreads are pretty popular), at a price point that many are ready to spend (below $2K is best, but it seems that below $4K is within reach of enough players; $12K guitars don’t usually get snapped up in a few days.
There also seem to be seasonal variation. For example, guitars usually move slowly for a month or two after Christmas, and there are other times of the year when sales volume seems to decrease.
For many people, there tends to be a big push in the last few weeks before a big move; I’d recommend that you aim to have your guitars sold a month before your move date.
Worst case scenario: you cant get all the guitars you want to sell gone, and you have to take a few more guitars with you.
