double date vs time of day

double date

noun
  • A (romantic) date that two couples go on together. 

verb
  • To go on a double date. 

time of day

noun
  • The greeting appropriate to the time of day. 

  • The time according to the clock. 

  • A loosely specified period of time, minutes or hours in duration, especially daytime, or point in time. 

How often have the words double date and time of day occurred in a corpus of books? (source: Google Ngram Viewer )