I’ve noticed that the values given by BTT in the past are very… hopeful 
You can change the settings at runtime via the M412 command. You can do this in your Start G-Code if you don’t use something like Octoprint or Pronterface.
I’d try the following in your slicers Start G-Code:
M412 D8 S1 R1
You can increase the value of D slightly (say 9 or 10) if you still have problems with 8mm.
I found in my testing that 7mm exactly is very optimistic.