The American phrase for this is contract-to-hire. You hire someone on a short-term hourly basis, with the understanding that this is a trial period that can be

The American phrase for this is contract-to-hire. You hire someone on a short-term hourly basis, with the understanding that this is a trial period that can be easily terminated by either side. The huge downside for the employer is that you're never going to hire away anyone from another company, so you're pretty much cutting out anyone who isn't very junior.