Oops, it doesn't look like 'postponement day' is a national day..

Other days

martini

Martini Day
stud

Stud Day
latina equal pay

Latina Equal Pay Day
lisp

Lisp Day
artists

Artists Day
fiancee

Fiancee Day
blanket fort

Blanket Fort Day
reading

Reading Day
bounce

Bounce Day
promposal

Promposal Day