Hi,
It is better to provide all the required documents at the time of registration. but if you don't have your character certificate it wouldn't affect your admission.
List of Documents for Verification given below :-
Most of the colleges have the requirement of both Gap Certificate and Character Certificate with their list of required documents. Character Certificate is issued by the school you completed your class 12th from and you can get your GAP certificate issued from any Notary. There is the unfilled GAP certificate affidavit on google if you search it, you can fill that and get that notarized.
Hope it helps.
All the best.
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