New job and time off requests, how do I go about it?

I'm supposed to start a new job on Monday through a staffing agency (a three month job/temp to hire) and I have something already scheduled in November. Should I tell the staffing agency or the job or both?

usa jobs
usa jobs resume
usa hotel jobs
usajobs
usa jobs federal government
usa job in ksa
usa jobs
usa jobs login
usa jobs gov
usajobs.gov
www.usajobs.gov
usajobs.com
usajobs
usajobs.gov official