be the first (person) to (do something)

be the first (person) to (do something)

To be very likely or eager to do something. You know I'd be the first to help you out; just ask me next time. She'll be the first person to admit that the program has flaws, but she still believes in it very strongly.
See also: first
Farlex Dictionary of Idioms.

(be) the ˈfirst/ˈlast (person) to do something

be very willing or likely/unwilling or unlikely to do something: I’d be the first person to admit that I’m not perfect. Mary is the last person you’d see in a pub — she hates pubs.
See also: first, last, something
Farlex Partner Idioms Dictionary
See also:
  • be first out of the box
  • first in, best dressed
  • for a start
  • first refusal
  • refusal
  • give (someone) the first crack at (something)
  • have (the) first crack at (something)
  • get the first crack at (something)
  • at first
  • first crack at