Let's discuss each of the provided statements one by one:

1. "If the election of the President of India is declared void by the Supreme Court of India, all acts done by him/her in the performance of duties of his/her office of President before the date of the decision become invalid." This statement is incorrect. According to the Indian constitution, even if the election of the President of India is declared void, all the actions taken by him/her in the performance of the duties of the office of President remain valid.

2. "Election for the post of the President of India can be postponed on the ground that some Legislative Assemblies have been dissolved and elections are yet to take place." This statement is also incorrect. Regardless of the status of the state legislative assemblies, the election to the office of the President cannot be postponed according to the Indian constitution.

3. "When a Bill is presented to the President of India, the Constitution prescribes time limits within which he/she has to declare his/her assent." This statement is incorrect as well. The Indian constitution doesn't set any time limit within which the President of India must declare his/her assent to a Bill.

In conclusion, none of the given statements are correct. Therefore, the answer is "None".