How quickly does Apple usually add RAW support. Sony A7C been out for a while now.

Apple never announces in advance, if and when RAW support for a new camera will be released. Usually the RAW support has been added within a year after the release of the camera, as a part of a system update for the newest system version. But not every camera will receive RAW support from Apple, even if the predecessor model has been supported.

While you are waiting you may want to convert the RAW files with the software provided by Sony to TIFF files, or use Adobe's DNG Converter.