According to a press release dated 15 December 2016, the Swiss National Bank has announced that it will unveil the design of the new 20-franc note (B356a) on 10 May 2017, with the notes entering circulation on 17 May 2017. The third denomination in the new family, the 10-franc note (B355a) is slated for introduction in autumn 2017.
Courtesy of Christof Zellweger.