Asked by suresh from china, I have a invitation letter, how can apply chinese Z visa in india

I am live in china, i will get one month L, it is expiry on May 15th. My company get work permit for me, china immigration give me the invitation letter (21.04.2014 to 20.05.2014), my company say i want go to india then apply chinese Z in chinese embassy (India) then come and get chinese working residence permit , how long take the time get my chinese Z (three months single or double entry).
Thank you for your help