The formula is still a bit wibbly wobbly and it will not give you an absolute determinstic score.
However, a few other phrases that you think are way more (or less) popular will help you get a qualitative (or relativistic) sense.
The default timeout is 60 seconds. So you will have to wait for at least 60 seconds to get a score. You can change this variable.
If you repeatedly search, you might exceed the rate limit for the app which could cause permanent banning of your IP.
A few dozen searches is alright. But remember that you may not be the only user.
If you think you found a bug (or broke it), report it via GitHub.