Yes. I, for one, would not want to rent a house where I intend to stay for months without knowing what I'm walking into.
If your heart is set on a house, you might want to start out at a hotel and shop around for a house once you are in Thailand. I would have a solid Plan B though because your chances of finding what you're looking for unfortunately are quite remote - unless you are willing to pay the full 6 months whether you stay that long or not.