Indeed, the call for young magi came with the agreement that they would become probationary members once accepted (after the current interview). It seems obvious to Wolfram that he will not be turned away (he is Overconfident, after all).
Wolfram first received a letter similar to this one. After he expressed his interest, he got a personal reply indicating that the Council of Fengheld was willing to consider him for probationary membership. He was to get there by the 15th day of June at the latest to be interviewed. This seems to be the interview.
Go ahead and edit your introductory post. I haven't read it yet, so its current content won't colour my perceptions.