Hello C.M. Lal Srivastava,
While appreciating the clarity and details you provided, let's also be clear about what the thread initiator is looking for - he/she is looking for a solution. All of us have given what the 'ideal/legal/accepted' practice ought to be. However, as I mentioned earlier, I have seen companies (needless to mention, headed by unprofessional characters at the top) mentioning clearly in Appointment/Offer Letters that the count will be from the date of acceptance OR, worse still, leaving this aspect vague to take advantage when an employee resigns. Most joinees don't care to read the fine print. Unless the thread initiator clarifies what's mentioned in the Appointment Letter, I guess all of us would be wasting our time by making countless presumptions...none of which may be actionable and realistic in the given situation.
Regards,
TS