If you father was having self income he can have self earned property. A person who has distinct self earning without any assistance of the joint family members or without gettng financial assistance out of the joint property can have self earned property and can also buy property in the name of the minor for the benefit of the minor.
You have not mentined whether the executant of the WILL is alive or not. Basiclly there is no such limit period of giving objection, the maintainability of objection is to be decided by the court taking into the facts and circumstances of the case. As Mr Kumar point out above the WILL will come into force only when the executant is dead.