Starting in mid-2018, LSAC will increase the number of LSAT testing dates from four to six annually. The 2018-2019 transitional testing year will extend from June 2018 through June 2019. There will be an additional administration in July 2019, which will begin the 2019-2020 testing year.
The schedule is at:
http://www.lsac.org/docs/default-source/jd-docs/testdateweb.pdf