The age-55 exception only applies to a distribution from a qualified retirement plan provided by an an employer from which you separated from service in or after the year you reached age 55. If you did not reach age 55 by the end of the year in which you separated from this employer, you do not qualify for the exception.
If you qualify for the age-55 exception, the plan administrator would normally know your age and separation date and would automatically use code 2 in box 7 of the Form 1099-R reporting this distribution.
