Can you sign NOIM form on the wedding day?

My friend got married recently but she felt like she was pressured by the groom's family as everything happened in just a day. The celebrant filled the NOIM form, did the vows and gave the couple a marriage certificate, all on the same day. Is it even legal? Don't you need atleast a month gap between the NOIM lodgement and wedding day? Marriage has not been registered yet so she wants to cancel her wedding. Is there any way?