Autofill Destination Range

The report size changes daily. So monday it maybe 50 entries long where on Tuesday it could 1100 entries. But row 15 is where I enter the data. So after I format O15:O16 I need to copy those two lines and start from O17 and go to the last O row(basically the Last row of P since O is blank). So if the last row of P is 90 it would autofill from O17:O90.