Your will take effect upon your death.
An Indian will is a static document, but it can be changes over time as the circumstances in your life and your family change. There is a document known as a “codicil.” A codicil in India is an addition to your will. The document basically states what items of your will you are changing. For it to be valid, you need to follow the same procedures as when you created your original will. A will and codicil should be kept together. If you are making substantial changes to your will, it is a good idea simply to create a new will rather than drafting a codicil.
An Indian will (and codicil) can be revoked. You can in fact create a document (with the same procedures as creating a will) revoking a will. If a will is physically destroyed it may be assumed that the will was revoked. If you revoke your will, the legal situation is as if you never had drafted a will in the first place.