Whi are out of custody on them and how long

It will depend on the location, the reason bond is being allowed and the specific terms of that bond.(even if they believe the person is an allowed risk for the bond.

In these cases the person is already convicted, but there is not room for them in the state prison. So they are allowed to bond out of county jail, waiting to report to prison.

The time for a bed to become available in prison, can be a week or two, or even a few months. It will depend on many things.