Okay your dentist just told you that your tooth is cracked.
He/She just told you that you need a crown.
Your first question is, "How long can I wait to get this crown"?
Well, here is the answer.
It totally depends.
A crack in a tooth will not stop on its own.
It will continue to progress until the tooth fractures.
What will continue to move the crack is chewing on the tooth that is cracked.
Therefore, if you stop chewing the crack will stop moving.
An all liquid diet will allow you to keep the crack from moving.
(Little side note here: grinding, even without
food in your mouth, can cause a crack to move as well.)
But unless you do that then the dentist has no idea how long until the tooth will fracture.
Bottom line is this, get your teeth fixed as soon as possible.
Financing the work is always a factor and maybe it can't get done right away.
Just know that the dentist has no way of predicting when and where you tooth will break.
If your dentist tells you you have a crack just be very careful.