In French, when you do things out of order, they use the expression “Ne pas mettre la charrue avant les boeufs”.
 
In English, it literally translates to “Don’t put the cart before the cow”.
 
However, the common phrase in English is almost exactly the same “Don’t put the cart before the horse”, it only replaces the animal.
 
This expression means to not do things in the wrong order and implies that the person being spoken to is impatient.

 

If you know someone who is excited to learn the piano, but their piano is out of tune, you could say “Tune the piano first, then learn to play. Don’t put the cart before the horse” to do things in order.