Before committing yourself to a position, have a talk with your potential employer about how many hours you can do per week.

After having a talk with your potential employer about how many hours you can do per week, commit yourself to a position.

Having talked with your potential employer about how many hours you can do per week, you should commit yourself to a position.

You should not commit yourself to a position before talking to your potential employer about how many hours you can do per week.

No sooner have you talked to your potential employer about how many hours per week you can do than you commit to a position.