When did the changes made by this act take effect?
The changes made by this act took effect on different dates as per the context provided:

1. The change made by the Constitution (Fifty-first Amendment) Act, 1984, s. 2, for sub-clause (b) took effect on 16-6-1986.
2. The change made by the Constitution (Seventh Amendment) Act, 1956, s. 29 and Sch. took effect on 1-11-1956.
3. The change made by the Constitution (Thirty-first Amendment) Act, 1973, s. 3 took effect on 17-10-1973.
4. The change made by the Constitution (Forty-second Amendment) Act, 1976, s. 47 took effect on 3-1-1977.
5. The change made by the Constitution (Eighty-fourth Amendment) Act, 2001, s. 6, for "2000" took effect on 21-2-2002.
6. The change made by the Constitution (Eighty-seventh Amendment) Act, 2003, s. 5, for "1991" took effect on 22-6-2003.