IF Statement to check for blanks first

I have 3 columns:-

Required Date, Actual Date & Status

I am using the following formula to place text in the Status Column to indicate whether I was early, on time, or late depending on the difference between the dates.

=IF(K47>J47,"LATE",IF(K47=J47,"ON TIME","EARLY"))

The formula works fine where I have 2 dates (i.e. on ein each of the first 2 columns), however...

I get the word LATE when the Required Date is blank and the Actual Date is filled.
I get the word ON TIME when both are blank.

I understand why I get this but I want the Status column to be blank unless both columns have valid dates.

That's spot on Ford, many thanks