It totally depends on the age when you are planning to retire. So let’s say if you are thinking of retiring at the age of 60 then you can start using the funds starting from 60 or 61. Please keep in mind that retirement funds are to be used strictly for that, i.e. retirement and nothing else. Don’t even think about using it for fulfilling any other goals or desires. Else you may find yourself in a very difficult situation at the time you actually retire.
Retirement fund is meant to support you and your spouse for the remainder of your non-employed life. After working hard throughout your life, I don’t think you will like it if you have to depend on someone else for taking care of your needs post your retirement. Post retirement is a beautiful period of life and is meant to be enjoyed carefree with your spouse or your loved ones.