first catch your hare
The first step is to acquire something; then, determine what to do with it. I know you're eager to plan on going to Yale, but you haven't been accepted yet—first catch your hare.
First catch your hare.
Prov. Do not make plans about what you will do when you have something until you actually have it. Fred: When I buy my house on the beach, you can spend summers with me there. Ellen: First catch your hare.