Many employment contracts prohibit working a week for another software company, possibly a competitor, without approval from the employer. I can start working

Many employment contracts prohibit working a week for another software company, possibly a competitor, without approval from the employer. I can start working for you - even if it's just for a week - only after I've quit my current job. So working that week before a hiring decision is simply not an option, even ignoring all the issues of time availability.