Also note that if you submit a flight plan more than 24 hours in advance you have to call.
Never done that. The notification has always worked on the day, even when lodged two or three days in advance.
It's in the back of the ERSA some where obscure.
ERSA GEN-PF-6.7 is about submission of Flight Notifications with ETD more than 21 hours in advance. Can't see any mention there about calling......