When should you cut your losses? Determine if a girl is a timewaster?

Hey guys, As I explained on a previous post, I met a girl through a hosting app. I invited her to stay at my place for a few weeks. However, it seems nothing romantic is going on between us, at best she is a friend. I told her that she would have to leave by the end of the month. I'm confident I made the right decision, since it seems she was only looking for a roommate as opposed to anything more than that. However, I wonder how you guys and Alex make this call. After 1-2 weeks if nothing is going on do you say, "Alright, it seems that this is going nowhere?" I think the main issue I see is that we don't have a "man to woman" connection. Is more a "friend to friend."