According to the latest notification about JEE Mains 2018 dates, the offline exam for JEE Mains 2018 will be conducted on 08th April 2018, whereas the online exam date has not been officially announced yet.
According to the sources, the online exam for JEE Mains 2018 will be conducted on 14th April 2018. This will be officially confirmed in the last week of November 2017.
Hope this will help..!!
All the best..!!