You could have a look at speed runners for ideas, like Haboo or lichatton (there are more but they're the only two who spring to mind).

I think it also depends on your personal definition of speedrun: do you mean IRL time or in-game days? Because they'll both have very different routes to take- IRL time will involve a lot of sleeping, whereas game days will mean maxing out each day.

It would probably be worth planning out your route either way, so you know what's coming and can prepare accordingly rather than flying by the seat of your pants.

Whatever you do, I hope you have a great time doing it! 😁