I don't see that the statement as necessarily meaning fulfillment. If you read it one way it could indeed be taken as "This ( that is, event taking place) is that which is spoken by Joel". Or you could take it in the sense of "This (meaning the following quote) is what Joel said in his book". I take it as the latter for the reason that the sun did not go dark, the moon did not turn to blood. Not to mention no blood, fire or vapor, dreams or visions. But Israel was at the end of the 69th week, so the 'end time' message of Joel was very relevant. (There may have been a partial or preliminary fulfillment at Pentecost, however, as the spirit was poured out on the Apostles.) Had they accepted Christ at that time, He would have soon returned and the times of refreshing would have began. Acts 3:19-21
'Repent ye therefore, and be converted, that your sins may be blotted out, when the times of refreshing shall come from the presence of the Lord;
And he shall send Jesus Christ, which before was preached unto you:
Whom the heaven must receive until the times of restitution of all things, which God hath spoken by the mouth of all his holy prophets since the world began.'
Had they repented as Peter called on them to do, they would have soon saw the (full) events of Joel's prophecy fulfilled in that day.
That isn't Darby or Scofield. That is Peter.
Are you a preterist Mr. Darby?
What Peter said in Acts 2:16 was; this is what was spoken of through the prophet Joel. The grammatical form is very clear, Peter is talking about the Apostles speaking in tongues.
It happened in Matthew 27:45-54 and the wording of Joel was NOT literal, but metaphorical. The color actually did appear.
Christ was ALREADY their savior so I don't know what you mean by "Had they accepted Christ at that time." However you conclusion is totally out in left field and NOT supported by ANY scripture.
Again I don't know who you are referring to by "they", but that day, v41 states; So those who received his word were baptized, and there were added on that day about three thousand souls.