Usually Universities will give a lot of leeway to students in terms of studying around their work. It's their revenue stream and they have a big stake in you being successful.
So I recommend you try that avenue first before thinking of involving your paid employment in your problems.
not asking at all, increasing my chances of getting hired but getting careless about M.Sc. schedule?
Don't do this, your masters is a major investment in your future and career, treat it seriously as such.