big day vs celebration

big day

noun
  • The day of one's wedding. 

  • A birding event in which teams compete against one another to see as many different bird species as possible in a certain area over the course of a day or part thereof. 

  • Any day on which something significant or momentous happens. 

celebration

noun
  • The observance of a holiday or feast day, as by solemnities. 

  • The act, process of showing appreciation, gratitude and/or remembrance, notably as a social event. 

  • The formal performance of a solemn rite, such as Christian sacrament. 

  • A social gathering for entertainment and fun; a party. 

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