Because there are several questions about notification, here is an excerpt from NMSC’s PSAT 2015 Official Guide with link following:
Program Recognition
NMSC uses PSAT/NMSQT Selection Index scores (calculated by doubling the sum of the Reading, Writing and Language, and Math Test scores) as an initial screen of some 1.5 million program entrants. The 2015 test scores of all students who meet entry requirements for the 2017 program will be considered. In the spring of 2016, NMSC will ask high school principals to identify any errors or changes in the reported eligibility of their high scorers (students whose scores qualify them for recognition).
Commended Students.
In September 2016, more than two-thirds (about 34,000) of the high scorers will be designated Commended Students. They will be named on the basis of a nationally applied Selection Index qualifying score that may vary from year to year. In recognition of their outstanding ability and potential for academic success in college, these students will be honored with Letters of Commendation sent to them through their high schools. Although Commended Students will not continue in the competition for National Merit Scholarships, some may be candidates for Special Scholarships offered by corporate sponsors (see page 9). NMSC will notify those candidates in November 2016.
Semifinalists.
Some 16,000 of the high scorers, representing less than 1 percent of the nation’s high school graduating seniors, will qualify as Semifinalists. Only Semifinalists will have an opportunity to advance in the competition for Merit Scholarship® awards. NMSC will notify Semifinalists of their standing and send scholarship application materials to them through their high schools in September 2016. Their names will be sent to regionally accredited four-year U.S. colleges and universities and released to local news media for public announcement in mid-September.
http://www.nationalmerit.org/s/1758/images/gid2/editor_documents/student_guide.pdf