You indicate from your question that you believe that the Second Coming is the parousia (Coming of the Holy Spirit). I agree with this.
It is clear from scripture that Peter preached that Jesus is sent to the individual believer through the Holy Spirit and abides with them, beginning at the time when they first repent from unbelief, Acts 2:38 and Acts 3:19-21.
Ac 2:38 Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.
Ac 3:19 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;
20 And he shall send Jesus Christ, which before was preached unto you: Ac 3:21 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.
John the Baptist’s ministry of “repentance” restores all things, including the kingdom of God (righteousness, joy, and peace in the Spirit) to believers, Mt 17:11, Acts 1:6, and Rm 14:17.
Mt 17:11 And Jesus answered and said unto them, Elias truly shall first come, and restore all things. (KJV)
Ac 1:6 ¶ When they, therefore, were come together, they asked of him, saying, Lord, wilt thou at this time restore again the kingdom to Israel?
(KJV)Ro 14:17 For the kingdom of God is not meat and drink, but righteousness, and peace, and joy in the Holy Ghost.
These verses have indicated that Jesus comes to an individual when they choose to repent from unbelief. At that time the Kingdom of God, or the personal relationship between God and Man is restored to God’s people.
The reason that most people feel that the Second Coming has not happened is because they feel that the Coming of the Holy Spirit, referred to in Acts, is not the Second Coming of Christ. This is unscriptural but common.
In addition to that, they feel that the “Second Coming” is the same thing as the “Day of the Lord”.
They are clearly different occurrences.
The Second Coming is for “salvation” (Heb 9:28) while the Day of the Lord is for Destruction/judgment, Joel 1:15 and 2 Pet 2:9.
Heb 9:28 So Christ was once offered to bear the sins of many; and unto them that look for him shall he appear the second time without sin unto salvation.
Joe 1:15 (KJV) Alas for the day! for the day of the LORD [is] at hand, and as a destruction from the Almighty shall it come.
2Pe 2:9 The Lord knoweth how to deliver the godly out of temptations, and to reserve the unjust unto the day of judgment to be punished:
(KJV)
They confuse the concepts discussed in 1 Cor 1:7-8 with the Second coming of Christ Jesus.
1Co 1:7 So that ye come behind in no gift; waiting for the coming of our Lord Jesus Christ:
8 Who shall also confirm you unto the end, that ye may be blameless in the day of our Lord Jesus Christ.
As can be seen, waiting for the “Day of the Lord” makes reference to being found “blameless”. Which is the end or goal of judgment as it pertains to Christians as is seen from 1 Cor 11:32.
1Co 11:32 But when we are judged, we are chastened of the Lord, that we should not be condemned with the world.
As Christians, we are “waiting” for something. However, we are not “waiting” for the Second coming.
As scripture mentions in 1 Cor 1:7-8, we are waiting to be conformed to the image of Christ and found “blameless” when our behavior is judged on the Day of the Lord.