How long does a UK settlement visa take to process?

I am currently in the U.S. I just sent out my application on Monday of last week. I received an email from the British consulate saying to allow them 3 working day to process it if it's deemed straightforward. They will email me with my tracking number for my pport and visa. It's been a week since and i'm worried they didn't think it was enough. I went thoroughly through my checklist they sent me. I know i sent everything they asked for. Anyone have any ideas? Is it possible to get my visa before the 50 working days they've mentioned in the email? I need some advice from anyone whose been through the process or knows someone whose had a UK visa. If you're going to tell me the same thing the email says it's not necessary. I'm only looking for answers from people who have experienced this. Thank you I do appreciate it.