This article from the Slott Report, https://www.irahelp.com/slottreport/age-70-%C2%BD-confusion-retirement-accounts, concisely explains the rules regarding when you have to take your first Required Minimum Distribution. Besides the Slott Report, another great resource for retirement planning is Appleby Retirement Consulting Inc. http://iraeducationcenter.com. Of course, the primary source materials for this area of the law is Employee Retirement Income Security Act (ERISA) and related portions of the Tax Code and Public Health Service Act (PHSA) but working your way through this area can be difficult.