|Darrell Impey UK|
If your BAB is 7, then it's not 8. 7 is in fact a lower number than 8, so you do not fulfill the prerequisite.
Jokes aside, any and all prerequisites about BAB always refer to the first number. The later number is always the previous number -5 and is just written out to remind you that you get an extra attack at that BAB, nothing more.