On the VOP timeline first: a probation violation in Georgia moves at the court's pace, and without knowing the original charge, the terms of her probation, and what the violation consisted of, there is no reliable estimate for how long she will be held. Her attorney or the Bleckley County court can give you the most accurate picture of where the case stands and what the likely resolution looks like.
On the baby: if she delivers while incarcerated, the newborn will be handed over to the Department of Family and Children Services for placement. Typically, the preference is placement with a family member, which means if you or another relative wants to care for the baby during her incarceration, stepping forward quickly and being approved through DFCS is the most important thing you can do right now. Contact DFCS proactively before the birth if possible. Being a known, screened, and ready placement option puts the baby with family rather than with strangers.
Once she is released, reunification with the baby requires going through an approval process. Courts and DFCS will want to confirm that she can provide a safe and stable home before custody is restored. That process can take time, so the sooner her legal situation resolves, the sooner reunification can begin.
This is a situation where having an attorney involved for both the VOP and the custody matter is worth prioritizing.