How many credit hours can a student athlete take as grey shirt before their clock starts ticking?

There's no universal answer to how many credit hours a student-athlete can take as a "grey shirt" before their athletic clock starts. The rules are governed by the NCAA (for US college sports) and are highly specific to the institution and the sport.

Key factors that determine this:

* NCAA Division: Rules differ significantly between Divisions I, II, and III.

* Specific School Policy: Each university or college sets its own internal policies regarding grey shirting. These policies can be quite flexible.

* Sport: Some sports might have stricter requirements than others.

* Individual Circumstances: The athlete's academic progress and the coach's assessment can play a role.

In short: You would need to consult the specific NCAA rules for the division and the university's athletic department to determine how many credit hours a student-athlete can take as a grey shirt before their eligibility clock begins. There's no single number that applies across the board.