It comes in approximately 29 days, Others answers have already stated it. However there is more to it. Also 29 days is not the time the moon takes to revolve around the earth it is about 27 days. read more
The interval period between a new or full moon and the next same phase, a synodic month, averages about 29.53 days. Therefore, in those lunar calendars in which each month begins on the day of the new moon, the full moon falls on either the 14th or 15th day of the lunar month. read more