This year CONTRAMID dates are May 17 to June 17, 2017 (West) and July 12 to August 12, 2017 (East). Fortunately DD wedding falls in between both sessions so DS will be able to attend.
Wow! Seems to be published much earlier than other years. Not doubting you - just surprised. For instance, the 2016 dates were published on April 12. http://www.nrotc.navy.mil/pdfs/OPNAVENOTE1530.pdf
Be prepared for slight changes.
Congratulations on the upcoming wedding and best wishes that your DS will be able to attend.