Count on 90 to 120 days processing time for a P2 visa (the paperwork you require to legally perform a paying gig in the U.S.); that's 90-120 days from the time USCIS (United States Customs & Immigrations Service) receives your application. While you will likely get approval in about 60 days, allow the maximum time to eliminate disappointment - unless you are willing to pay an additional $1,000 US for "Premium Processing". You must have confirmed engagements in order to apply, and for the most part, you will have to have these on a completed T2C contract. Your P2 can cover up to one full year of bookings if you send in an application listing at least one confirmed engagement for each month of that year.
The cost of your band P2 will be $320 USD plus a $25 CDN fee for administrative costs. (Newly increased rates as of July 1, 2007). If you have techs or roadies going with you there will be additional fees. The Performing Arts Visa Task Force of which the AFM is a part opposed this increase but was unsuccessful in stopping it.
If you have a P2 and during the course of that P2 you are offered additional work, you may be able to get the extra dates added on, but that's not a given - so get in touch your AFM local as quickly as possible to see if you can get the new dates added.
Remember to take your membership card or dues receipt with you on the road in case you need to verify your AFM membership.
An act before the U.S. Congress - Arts Require Timely Service Act (ARTS Act) - would require that the USCIS actually process an artist visa within 30 days. If not, it would be placed within the Premium Process Service with the $1,000 fee waived.