How do I know when a new server starts?

I think so rare new state opens after 14 to 15 days

I don't know how to tell when a new one starts. But if you check the state map you can see all the states available. If you find the highest number that should be the newest state. You could check this every day to see if new ones are added.

Start a new account and then choose to teleport to the new state when you want to.

To find the state map go to the world view then tap the pin icon on the lower left. This will show you your current state. Then tap the world (globe) icon in the same lower left position to see an overview of all states.