OK so 90km is around the distance I race on my MTB, so anywhere between 3:30 to 4:30 hours of exercise time. Obviously racing on the road is a lot quicker but the fundamentals should be roughly the same.
I’d eat more the day before, making sure I had a high carb pasta based dish the night before.
For an 11:00 start I’d want to finish breakfast 3 hours before hand, and again this would be larger, but not stupidly so, than normal. Coffee, juice, large muesli bowl, 3 pieces of toast.
I’d drink a weak sports drink mixture on the drive to the race and consume a power bar or similar 30 minutes before the start.
As I said sports drink in the bottle/camelback and a gel every 45 minutes during the race.
Just some background that may help. As said play around with a routine during the weeks leading up to the next race and see what works for you.