On page 42 we learn that Ozma's birthday is coming up on the 21st of the month. We know from page 15 that it's currently August. If Oz is on the same calendar, then Ozma's birthday is August 21st.
Polly: "You have some queer friends, Dorothy."
Dorothy: "The queerness doesn't matter, so long they're friends."
(p. 184)
Dorothy et all are coming up from the south. Foxville, the furthest south dot on this map is described by Dorothy as being a two hour walk from Kanas.
The full map is here:
https://curtiswrightmaps.com/product/the-marvelous-land-of-oz-and-the-magical-countries-surrounding-oz-2/
After two towns, two of Dorothy's party have been transformed by magic. Button Bright sports the head of a fox. The Shaggy Man has the head of a donkey.
The donkey king's palace is described as having "mats of woven grasses on the floor" ... with "no other furniture at all." So I'm picturing tatami mats.
(p. 80)
On page 42 we learn that Ozma's birthday is coming up on the 21st of the month. We know from page 15 that it's currently August. If Oz is on the same calendar, then Ozma's birthday is August 21st.