cart before the horse
(put) the cart before the horse
to do something that should happen later before other things.
Barnhart is putting the cart before the horse by building a stadium before a team has agreed to play there.

to do things in the wrong order.
Deciding what to wear before you've even been invited to the party is rather putting the cart before the horse, isn't it?

[TahlilGaran] English Idioms Dictionary ▲

cart before the horse (to put)
{n. phr.}, {informal} Things in wrong order; something backwards or mixed up. - An overused expression. Usually used with "put" but sometimes with "get" or "have".
When the salesman wanted money for goods he hadn't delivered, I told him he was putting the cart before the horse.

To get married first and then get a job is getting the cart before the horse.

[TahlilGaran] English Idioms Dictionary ▲