Just like our October trip here in the Philippines ( from Thailand), we booked our ticked last March when Cebu Pacific had this promotion. We were originally scheduled to leave in December but because of the promo flights, we adjusted our scheduled instead.
But there are times when trips are unplanned and end up booking last minute flights. I heard there are still cheap flights that caters to these so called unplanned trips and you can even book your last minute hotels. But as a rule of the thumb: Plan ahead to avoid the rush and the hassles.