'Up to 2 months' is probably a
very conservative estimate.
The following is a direct quote from the US embassy website (with the bold and italic text highlighted by me):
"If the conviction(s) results in the applicant being found permanently ineligible to receive a visa, it will mean a lifetime exclusion from the United States unless he or she obtains a waiver of the permanent ineligibility from the United States Department of Homeland Security Customs and Border Protection (DHSCBP). The granting of a waiver is not automatic and is based on several factors, including nature of the crime committed, sentence served and the period of time which has elapsed since the conviction.
If a favorable recommendation is made to DHSCBP for a waiver of the permanent ineligibility, the application will take a minimum of eight weeks to process; some applications may take longer.
Please note: Delays in processing can and will occur. The processing times quoted are approximate and cannot be guaranteed. It is important that you keep this in mind when applying for the visa. It will not be possible to expedite a case simply because an applicant has not allowed sufficient time for the application to be processed."
Source:
http://www.usembassy.org.uk/cons_new/visa/niv/ add_crime.html
Chris