Some professions have signing bonuses - they usually make it known when you‘re in the Recruiting Office. In my local office, they‘ve got a big bulletin board filled with all the different professions currently offering Signing Bonuses. Of course, 95% of them seem to be skilled occupations, requiring a college or university degree. But that only makes sense, really.
So unless you join an MOC that has a signing bonus, don‘t expect a cheque to show up at your door just for signing up.