Just went into the Apple Store and asked a couple of members of staff about if they "knew what time it's launching tonight". However they really didn't seem to think it would be and said that even their card terminals had not been replaced with ones that would support contactless / Apple Pay which they were sure would be happening for day 1. They and the managers had been told to say July 31st.
However, I asked them to double press the side button on their watch, and on one of theirs (UK) it did come up with the "go on your phone to add cards to Apple Pay". So who knows!