It depends on the job market. In France, engineers usually have 3 months notice period. So if you hire someone who already has a job, you have to wait for 3+ m

It depends on the job market. In France, engineers usually have 3 months notice period. So if you hire someone who already has a job, you have to wait for 3+ months for the new hire to leave the previous job. If that's a bad choice and you have to fire, you have to start again for the next candidate.