The period of abandonment for accounts established pursuant to 26 U.S.C. §401(a), et seq. (commonly known as Self-Employed Retirement, or Keogh, Plans) and 26 U.S.C. §408(a), et seq. (commonly known as Individual Retirement Accounts or IRA's) may not begin until such time as distribution of all or part of the property constituting the respective account shall be, under the terms of the retirement plan, mandatory.