Representative of an Overseas Business Visa

Hello,
Can anyone clarify, to apply for a Representative of an overseas business visa shall the person be employed by the company for certain time (if yes, so what is the period) or can be employed prior to visa application, i.e. person can be employed exactly for this position, has a job offering letter and did not work for the company before.
Thank you in advance.
sega_isr

Reading the Representatives of overseas businesses guidance should help.