My iphone says it is unavailable. How long do I have to way until it allows me to re-enter my passcode?

It will tell you on the screen. If there is no timeout listed you must restore the phone. If your device has iOS 15.2 or later installed, you can reset it without a computer; check out this link→How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support. Otherwise you will need a computer:

See this Apple support link→If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support

Or watch this companion video ⬇️

After restoring the phone using one of the methods above you can restore your most recent backup.

It doesn’t matter how long you wait, that won’t happen.

You need to erase and restore it.