A boy becomes Bar Mitzvah on his 13th hebrew birthday. The sedra on which he can have his first call-up or Aliyah is determined by his date and time of birth. The United Synagogue has a Bar Mitzvah Calendar on their main Bar Mitzvah page which can be used to help determine the appropriate date and haftorah for a barmitzvah given the boy's birth date, and the Wardens can confim the correct date with you.
Please discuss all aspects of your son's Bar Mitzvah with the Wardens who will be happy to help.
At the end of the service, the Priestly Blessing is said to the Bar Mitzvah. This can be said by the service leader or the parents, and a recording of the blessing is available.