The sooner, the better means the faster the response or the arrangement, the more convenient it is for the speaker.
For example:
The green man says: I was just wondering if we could go to the new restaurant around the corner?
The friend says: When?
Green man: The sooner the better. I have to do so many things at the office, so after I finish, I will get to the restaurant as soon as possible.
Friend: Deal!
家族や友達にも気軽に使えるフレーズです。
日本語でも敬語や標準語、地方の言葉などにして会話がなされています。
たまにはインターナショナルの言葉にして日々の趣味の一つにしてみませんか?