Hi aspirant,

Honestly speaking there is nothing you can do now unless and until both the examinations are in different time slots. Actually NDA is a national level examination and dates for same are released almost 6 to 7 months prior to the day of examination and if the request other educational Boards not to schedule any examination on that day. Moreover 10th April is a Sunday and no board examination generally is held on that day. You are requested to see your routine once again because I doubt that there should be no board examination on that day and if there is then you can do nothing about it. However you can appear for the next phases of examination as you still have multiple attempts left for the NDA exams.

Hope it helps!