I was told by a reference that they were contacted, how long should I wait for an offer after the fact? (Role as an Engineer in Training)

I interviewed a company, they said it would take them a week to contact references, and then the next day I was told they were contacted by one of the two companies I did really well with. How long should I wait for an offer, before giving up on them in my head? Obviously, I'm going to continue to apply to locations for engineering.

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