From experience I wouldn’t experiment with caffeine this close to a race, I’ve found it’s had negative impacts.
I can’t say how or why but I worked on caffeine peak time and when to supplement a few times and it never worked.
However, towards the end of 100km gravel ride recently I took a caffeine shot and it worked. The thing is I had a normal cup of coffee in the morning and caffeine didn’t feature in my nutrition strategy other than “in case I need it”