G4Games lists the details of an alleged raffle being held by Vodafone in Germany, which runs from July 1st to September 30th. Handsets are listed with a numerical point value with both the Xperia Z3 and Z3 Compact awarded a points value of 1.5. This indicates that both handsets should be available before the end of September, most likely after an announcement at IFA.
The points are being awarded when shops reach individual sales goals in six categories. The overall winner will earn a trip to New York for a Black Friday shopping spree. All Vodafone stores will automatically participate in this sales competition.
There is always the possibility that this is a placeholder in case the phones are announced and launched in September. And of course, there are always question marks over the legitimacy of a screenshot. For now, take it with a grain of salt, but a September-October release does sound most likely.