"As new WildFire signatures are available every five minutes, this setting ensures the firewall retrieves these signatures within a minute of availability."
Meaning if the WildFire checks for verdict at 06:00 PM it would next check at 06:05, however if you submit a file at 06:06 - WildFire would check at 06:10 but your verdict will come at 06:11, which would be fetched by WildFire at 06:15 - hence 9 minutes since you submitted. So 5 to 10 mins depending on your time of submission.