Here are some historical rate charts that date back to, like, forever:
https://fred.stlouisfed.org/series/MORTGAGE15US
https://fred.stlouisfed.org/series/MORTGAGE30US

Now seems like a good time ... how much lower could you honestly expect them to go? Not to mention, if you're dealing with a decent broker, they'll get you the lowest rate available between the time you start the process and the time you sign the dotted line anyway.