If you reach the required age, your plan administrator should do your calculations and distribute the proper amount. If you have any doubts, contact them.

Required Minimum Distributions (RMDs) generally are minimum amounts that a retirement plan account owner must withdraw annually starting with the year that he or she reaches 72 (70 ½ if you reach 70 ½ before January 1, 2020), if later, the year in which he or she retires. However, if the retirement plan account is an IRA or the account owner is a 5% owner of the business sponsoring the retirement plan, the RMDs must begin once the account holder is age 72 (70 ½ if you reach 70 ½ before January 1, 2020), regardless of whether he or she is retired.

Retirement plan participants and IRA owners, including owners of SEP IRAs and SIMPLE IRAs, are responsible for taking the correct amount of RMDs on time every year from their accounts, and they face stiff penalties for failure to take RMDs.

Please see this LINK for more information.