What is the process for applying for a I-131 Travel Document?

I am in the process of moving from Canada to the U.S.A. on a K3 spousal visa. Once I come into the U.S.A. and apply for permanent residency I apparently cannot leave the country for awhile. I want to be able to come back to Canada for a couple months to work until my Social Security Card is ready. Does anyone know the process of applying for a I-131? As far as I can tell, I have to apply for it, have my biometrics done and then I can leave and have the I-131 approved document sent to a consulate in Canada. Is this correct and if so, how long does it normally take to apply and get an appointment for my biometrics? I know the processing time for the approval is 3 months but just wondering how long it'll take for an appointment for my biometrics. Hope this makes sense. Thanks for any help.