Right now the selection process for the year 2019-2020 is going now. The admission forms for the academic year 2020-2021 will be released later in 2019. For the academic year 2019-2020 the admission forms were available from October to November of 2018. So you can expect admission form for the academic year 2020-2021 to be available from October of this year. And the exam can be expected to be conducted in the month of January 2020. I'm providing a link below you can go through it.

http://admissions.nid.edu/NIDA2019/download/BDes_AdmissionsHandbook2019-20.pdf