The rules permit:
However, you may only apply this advance from advances in the career profile. This limits the Initiate career, clerics by another name, and leaves these proto-priests unable to cast divine magic in their first career. The +1 to the Mag characteristic is not available until exiting to the Priest Advance Scheme. The houserule is to allow Initiates to take the +1 to Mag so that these proto-priests may cast spells.