Hi,

The information brochure of nta JEE main exam do not describe any particular date of certificate. They information regarding certificate they have given is " Gen-EWS, SC, ST, OBC and PwD candidates will be required to produce original certificate as per prescribed formats issued by the competent authority at the time of Seat Allocation Process as well as at the time of admission, failing which they will not be considered for admission."

so according to this you have to provide certificate at the time of seat allocation and admission. So you can use your certificate issued on 15 January.

hope this helps.