Meaning/Usage: Asking from when

Explanation: This one is a little difficult to explain. It is usually used when you are surprised by someone's action or words. When you know a person does not usually do something, you can start with "since when." This would indicate to the person that you know that they usually don't do this, but want to know when they started doing it.

"Since when have you been interested in my opinion?"
"Since when have you been coming to this gym?"
"Since when did you become so good at tennis?"

A. "I will have to go home soon, I have chess club tonight."
B. "Since when did you become so interested in chess?"
A. "I tried it with my uncle and loved it."
B. "Well, we'll have to play soon, I like playing too!"

Other Common Sentences

"From then until now."