earn (one's) spurs
To prove one's skill in a particular area. Once you've watched the triplets for an entire day, then you'll have earned your spurs as a caretaker, as far as I'm concerned. After getting my bachelor's degree, I earned my spurs as a teacher by working in underfunded urban schools.
earn one's spurs
Fig. to prove oneself. After that rodeo, all the cowboys agreed that Sally had earned her spurs. He felt that he had earned his spurs when he received his Ph.D.
win/earn your ˈspurs
(formal) become successful or famous: You’ll win your spurs as a teacher if you can control class 5.