How long it will take to attest my document in Beijing?

hello sir ..
I am a student and doing my MBBS (2006) in china. On December 17 2010 i'll complete my MBBS and for internship i'll go back Bangladesh for 1 year. Now i want to know do i need the attested my all of the documents which will give my University (mark sheet, provisional certificate) OR after finishing my internship when i'll back china on 2012 (January)?
And please tell me how much time you'll take because i'm living in Nanchang and it's so long distance for come in Beijing and also BOOKING TICKET for bd ... What Documents you need to Attested?