Clara had prior knowledge of the Doctor. (She) was conceived as a human connected to your timeline, and so had access to the cosmic nature of the Doctor. She understood a little about how he was. And as she was already with Matt (Smith), she knew the Daleks and the TARDIS. Now we have someone who knows very little about the Doctor.
Capaldi says that he has met the new companion, but that is all the info we have for now. It’s not like he’ll get much time with his new companion anyhow – Capaldi will be leaving the show in the not too distant future.