The teacher will read you your book when she finishes reading the other one.
She'll read this book to you when she's finished reading the one she's reading now.
この場合、次のような言い方ができますよ。
ーThe teacher will read you your book when she finishes reading the other one.
「先生は別の本を読み終えたら、あなたの本を読んでくれるよ」
ーShe'll read this book to you when she's finished reading the one she's reading now.
「今読んでいるのが終わったら、あなたにこの本を読んでくれるよ」
ーYou have to wait your turn.
「順番を待ってね」
to wait one's turn で「順番を待つ」
ご参考まで！
She will read this book to you when she finishes reading that one
＊先生は女性の方であれば
She will read this book to you when she finishes that one
先生は、先にあの本を読み終わったら、
この本を読んでくれるよ。
読み終わる＝to finish reading
日本語の通りの順番でWhen she finishes reading that book, she will read this one to youでも問題ないです！
ご参考になれば幸いです！
カナダ 
アメリカ合衆国 
