Hi aspirant,

You do not need to wait for the board examinations for JEE main examination to happen. You can complete your application form leaving those particulars empty or write N/A. See the thing is that after the conclusion of examination the counselling process for seat allotment happens, where candidates are required to show their certificates and marksheet to confirm their eligibility. So even if you leave those fields empty it will not create much of a difference. Adding to it appearing candidates will be able to get there marksheet or certificates by the end of April or May only but that application forms closes by end of March, so the candidates have an option to upload the documents anytime later in addition to their application forms.

Hope it helps!!