Supercharge.info lists the opening date as 2014-10-27.
According to messages on the TFF-Forum it's definitely October, but I don't see any definite evidence for the 27.
August 1, 2024, picture of the permit request in the official journal.
August 12 picture of the gabarits for the transformer. August 24, a different picture.
A webcam was installed to follow the construction, starting from September 2
Around October the construction seems to have started.
October 8, pictures of the construction on location by herbhaem. Also second post
More pictures October 11, , October 18.
October 23, pictures inside the transformer house
October 28, the stalls are installed, the lines are being painted.
October 29, Tesla seems to be testing the chargers.
October 31, user teslator reports that the chargers are working.
On November 1 there was a double opening ceremony for Maienfeld+Beckenried, with pictures shared by elekktrisch.
All those pictures show a setup with 6 stalls, including the forward-parking stall. The 2 additional stalls along the main road as well as the 6 along the secondary road were all installed later.
On April 12, 2017 user Aldus shares that the +2 upgrade has started. There's a picture of the gabarits to increase the size of the charger housing. There's also a link to a PDF on the town website but it's a dead link now. On April 13, the same user reports they asked the hotel and learned there would be 8 new spots.
On May 7, user Martinsteiner shared pictures of the signs that were posted saying the station would be out of service on May 9. We also see that all foundations for the 8 new chargers have been installed.
On May 28, user elekktrisch shared pictures of the completed setup.
I can't find any message confirming when the new chargers were first working.