How to ask time using present perfect continuous

Question

Today, while teaching one of my students about present perfect continuous one of them asked how to ask time while using present perfect continuous.

I want to ask what was the time when he started say playing football. So far I have come up with 2 solutions to my dilemma

1. Since what time have you been playing football? or
2. What time have you been playing football?

or asking "how long have you been playing football would work?

I learned that if asking time one should use "what time"

but since I am not a native I must apologise if I am mistaken.

So my dear friends tell me how am I supposed to phrase the question with perfect grammar?

Answer 1

"What time have you been playing football since?" would be correct if you wanted to use the present perfect continuous. (In formal usage, "since" would tend to move to the start, resulting in your first sentence.)

However, the most usual wording would be "What time did you start playing football?".

"What time" could also be replaced with "when", but "When did you start..." would be ambiguous - someone might answer it with "In 2016".

Without the "since", "What time have you been playing football?" would be asking about a repeated or habitual situation (for example, if it's a daily or weekly occurrence) rather than what time the current match started.