I have been offered a teaching contract in China and instructed to obtain a Z Visa from here.

All of my documentation has been sent to the school. I have a letter of intent and hope to sign a contract soon I cannot come to the consulate during the given hours as I am teaching at a local school, here in Lagos. I need to be advised about the process, what I need to do, to bring and how long it will take. I am expected to begin my job in China by February 18th 2013. Please advise me asap.