Can I start working on Z Visa issued by Chinese Embassy in India till i get my permanent Visa

Hi I have already got my work Zfrom India and soon will be working in Shanghai. However, my employer has told me that as per regulation, after landing in China i can not join the company until i get a work permit and resident permit, which will take 2-3 weeks. Due to which i can not get my salary of that duration and also their will be a employment gap of same duration. I want to Know can i not join a company with the Z (1 Month) issued to me by the Chinese embassy till the time i get longer duration type. Do I really have to wait to start working for so many weeks?