Possibly by the first stop, even, if she doesn't mind an illusion that wavers slightly, though definitely by the second stop.
The little fishing village at the first stop is situated amidst numerous lakes and rivers full of creatures that glow faintly in the starlight. They'll stay for what their internal clocks tell them is a day, while Sarati trades and does arcane things on the ship, though no sun rises and the bright stars wander in their own separate patterns.
Tetsuma offers to teach Dayo the beginning of water walking as long as they're there.