この場合のお礼は受取りの確認の意味もありますのですぐに出すべきです。形式はどうでもいいと思いますが、たとえば
I received on MM/DD/YYYY XXX I had requested, and I thank you very much for your quick response. I really owe you for the education I received at your school, which has helped me so much afterwards.
お礼
参考になりました。有り難うございました。