请问学校办I-20一般要多长时间

Baffulo网站上的介绍，根据这个流程不是要2-3个月了吗，签证什么的不全都来不及了吗。

Below you will see why the process takes so long (THE I-20 PROCESS):

Applicant submits ALL application materials to Assistant Director of M.A. Program
Assistant Director of M.A. Program submits application materials to International Admissions (2 to 6 weeks)
            
Application goes into a database in Washington, DC
From there, the student is entered into another database
Afterwards, the I-20 is requested from Washington, DC by UB International Admissions. The student is then given a SEVIS ID#, and the I-20 is sent back to UB (Another 4 to 6 weeks to process packet)
            
UB International Admissons sends the I-20 packet to the student
International admissions then issues the Admissions packet which includes: I-20 acceptance, the Certificate of VISA Eligibility, information about International Orientation, on-campus housing, international student clubs, and health insurance
Upon receiving the official Admission Packet, student should make arrangements to register for International Student Orientation, apply for your student VISA, and arrange to come to Buffalo, New York.