Depends on how she sets it up, various ways. She can pay the whole lump some, or maybe have to pay the first and last month's premium, or maybe just the first month's premium. Does she not have a credit card? I would say, to be on the safe side, to bring about $300 cash if not. Probably way too much, but you never know.
You can call around and get a quote in the morning. Then you can ask them how they handle payment, so you can be prepared.