Australian Migration and prospective visa waiting times
Unfortunately currently the waiting times for an Australian Migration, Australia prospective marriage visa are taking up to 7 months to award and this is if the documents provided are perfectly done and the submission of the documents is correct. An Australian marriage visa can be amazingly difficult and time consuming and it should be understood that it takes time and you should get yourself ready for the long haul.
You can save yourself the long wait by using a professional service like Key Visa Thailand to process the application and present it to the Australian Embassy in a way that will speed up the process and make sure all the documents are in place so you are less likely to get delays. The Australian Embassy are currently quoting anything up to 12 months for an Australian settlement, migration visa to be awarded which is a staggering amount of time to be without your Thai wife or Thai fiancee so let the experts take hold of the rains and do the Australian visa application for you with no problems.