expression
since some time ago; for a while now
Indicates that a state or action has been continuing from a point in the recent past up to the present. Often used when the speaker has just noticed or wants to emphasize the duration.
See also: 先ほど (さきほど)
先ほどから雨が降っています。
It has been raining for a while now.
先ほどから電話が鳴っているのに気づかなかった。
I didn't notice the phone had been ringing for some time.
先ほど means 'a short while ago' and refers to a point in time, while 先ほどから focuses on the duration from that point until now.
More casual synonym; 先ほどから is slightly more formal and polite.
Compound of 先ほど (sakihodo, 'a short while ago') + から (kara, 'from').