I graduated in Dec 2009 and my mom got multiple tourist visa for my graduation for 5 years but she couldn't make it for that day due to financial problem. I have heard that she has to come within 6 month of date of visa issue otherwise visa will not be valid. Is that true? or can she come later because I am thinking to call her after 2/3 months or a year? Please suggest me if anybody has any experience or information regarding this.