Is it essential to mark the evidences prior to the cross

1. You can produce such original/certified copies of the  documents during the process of cross examination of the complainant which will automatically be noted as 'Mark" and then while during the oral argument you can assert them to be relevant and pray to have them marked as "Exhibits".

Produce the relevant Original / Certified Copies of the documents at the time of evidence/ cross examination. Also do submit a memo to the court mentioning about the above documents so that it comes to record. Do not wait till the time of argument as it is noticed that many corrupted judges bypass the argument if the party is fighting in-person.

It is always advisable to take assistance from a learned practitioner even you opt to fight on your own. This is just t ensure proper adherance to the legal process & procedure.