To apply for the NTSE Stage 1 Exam, one must be a student of class 10. The NTSE application process commences in August, every year. Follow the link given below to check complete details on the NTSE 2018. 

https://www.entrancecorner.com/results/ntse-result/

You can apply online as the application window opens in the month of August and for this session NTSE stage 1 exam is already done. To know more about the same in detail, you can go through the below link -

All about NTSE

Good Luck!!!