when we use "since", is it always with the progressive tense ?
I can't see why you think so, dear.
Since as a preposition: Since when have you been learning English? (sentence in the progressive form) How long is it since your visit? (sentence in the present) Since last year I have been muzzled. (present perfect)
Since as a conjunction: I have spoken English since I was a baby. How long has it been since you last turned up.