I have seen some negative feedback previously about online 90 day reporting, so I thought I would provide my experience.
I decided to do the report a week early online in case I was unsuccessful and needed to go to Bluport.
The online system is very easy to use, I received an almost immediate receipt acknowledgement and it was approved the day after.
It could not have been any simpler really.
If you have had problems in the past it might be worth giving it another try.