Do I need to book for a date to deposit a visa application?

Sir, my file for application is ready for a Z type. Do I need to book for an appointment or may just come and deposit? In Douala they insisted I should book,but gave me the 10th of September 2015 . schools would resume on the 1st of September hence I may miss my contract. Can the office in yaounde do express service for my case? Thanks