Hi all, this is listed as a May release in the June 1975 issue of Australian Record & Cassette Monthly, and it entered the national album chart in the chart dated 12 May 1975, so it would have been released the first week of May at the latest; it could have been mastered earlier as T-V-J says, but perhaps release was delayed for some reason.
Hi, Wax Museum the first copy I'm referring to here, now that I think about it, was probably bought in 1975/76. So, it was most likely a repress. This copy came my way from someone that was dumping their collection so I have no idea of when it was actually bought. However, the other album you commented on -Dylan's Nashville Skyline- was in the same batch. It is hard to tell sometimes without going all trainspottery (that should be a word) and getting out the magnifying glass to examine the deadwax and research it on the net.
The first version I bought looked more like the Kiwi version I uploaded (linked below) but with an inner sleeve. This New Zealand copy also came from the same place as the other two and while I'm glad to have them I have no idea of the history of these albums because I didn't actually buy them new.
This is a repress (I think) as my previous copy (original) had a laminated cover and this one doesn't. Yes, I did own this before the days of punk made me espunge it from my collection for fear of cultural condemnation. Luckily, it has bounced back to me and now with no peers to fear I can safely be fond of it again.