Back glass on my 12 mini is broken how long does it take to fix ?
How much does it cost ?
iPhone 12 mini, iOS 16
We are not Apple but end users like you. We cannot know.
Time for service depends on who does the work (Apple or an Apple Authorized Service Provider), parts availbility, even where you are in the world.
Please start here: iPhone Repair & Service - Apple Support
Back glass damage is among the repairs the estimator on that Apple page can process: