1
general::
The most important task gets priority, as in I very much wanted to see that movie, but first things first? the paper's due tomorrow. This adage was first recorded in 1545.
American Heritage Idioms
2
general::
Phrase(s): First things first.
Prov. Do things in the proper order; do not skip things that you should do first. • Jill: Should we go to the museum first, or should we go shopping? Jane: I’m hungry. Let’s eat lunch before we discuss it. First things first. • First things first: read the directions carefully before you try to assemble the bookcase.
McGrawhill's American Idioms And Phrasal Verbs