Acknowledging the Arrival of the Month of Ramadan during the Day

Q: Assuming it is announced, before the canonical noon, that today is the first day of the month of Ramadan, what is one’s duty on that day?
A: Assuming one hasn’t, until then, committed any deed which would invalidate one’s fast, obligatory caution dictates that one ought to make one’s intention to fast and then actually fast on that day in addition to observing its compensatory fast (after the month). However, assuming such a deed was, in fact, committed, then one’s fasting would be void; however, out of respect and honour to the month of Ramadan, one must refrain from committing any action which invalidates fasts until the maghrib adhan and observe the required compensatory fast after the month.