In Leviticus 23 (& Num 28) and elsewhere, the feasts throughout the year were to be memorials that concerned the Exodus and wilderness journey. Since they are set in real events, I believe they provide a type for us of the events of the 1st advent and much of the symbolism found in Revelation. Before Leviticus describes the feasts, the Sabbath is declared - and each of the feasts contains one or more sabbaths. (Which is a study in itself)
The first clue which is most obvious is Passover - since our Lord was crucified on that day - the Passover Lamb we know is Christ. The 1st 2 days which follow passover are sabbaths in the week of unleavened bread. These would seem to coincide with the 2 days the Lord was in the grave. Leaven here I think depicts life so unleavened bread is the death of the Lord. It is noteworthy that none of the other feasts have 2 sabbaths in a row. On the 3rd day He rose, but Israel was resting for the 2 days He was in the grave. The Passover deliverance from Egypt is the type for our deliverance from sin and bondage to the devil by the crucifixion of our Lord.
Firstfruits or Pentecost we also know symbolized the arrival of the Holy Spirit. This is the spring harvest of the former rain in which their offerings brought the people acceptance from the Lord. This feast specifies a new meat offering and a bread offering with leaven (hence a new creature with new spiritual life). After this reaping the corners of the field were to be left unreaped and they were not to glean the rest of the field after the reaping but leave it for the poor and the strangers. Israel was the firstfruits of the harvest to whom the gospel was preached and the Gentiles are the poor strangers who gleaned the gospel after them. Thus we have the evidence the new covenant was in force with power.
It is 5 months later that we come to the Feast of Trumpets which was a memorial and also a sabbath - since the 1st of every month was to be a sabbath. This memorial is not specified but I think it is the first battle with the Amalekites. Trumpets and war seem to be connected and the 7 trumpets we have in Revelation I think are related to this feast. It seems to be a picture of our battle with the devil and overcoming victory in Christ. The saints in Smyrna were to suffer persecution from Satan for "10 days". Rev also mentions locusts who torment men for 5 months. This perhaps represents the period between Pentecost and the next feast or the time before Israel was judged for their sin in rejecting Messiah. (The Roman armies also beseiged Jerusalem for 5 months)
On the 10th day following is the Day of Atonement. This is a day of redemption but also one of judgment for the disobedient - a day of reckoning. It is a day of affliction (fasting) and is preceded on the 9th with a sabbath. Those who disobey and do not fast are to be cut off while those who break the sabbath are to be destroyed. It is the only feast in which a curse is attached. Famine and war marked the desolation of Jerusalem but also the fullness of the redemption brought in the 1st advent and the establishment of the kingdom in power. The 7th trumpet thus marks when the victory had been achieved. I do not think the 7th trumpet is related to the 2nd coming since it is specifically given as a Jewish memorial.
On the 15th of the 7th month is the Feast of Tabernacles or Ingathering, the fall harvest of the latter rain. This feast has a sabbath on the 1st day and on the 8th day, both of which were to be a solemn assembly of the people. Inbetween the people dwelt in booths like they did in the wilderness and were to feast each day and rejoice. I see this as representing the current Church Age between the 1st and 2nd advent of the Lord, when the saints now indwelt by the Spirit, rejoice in His blessing. What is interesting to note in this feast is that it begins with 13 bullocks offered and each day one bullock is taken away until on the 7th day only 8 bullocks are offered, while the 2 rams and 14 lambs remain the same. Then on the 8th day only 1 bullock with only 1 ram and 7 lambs are offered, which is 1/2 of the previous rams & lambs.
The wilderness journey which we are told is the type, began when Israel refused to enter the promised land and ended with only their children actually entering in. Thus 1/2 of the people entered while the rest had their numbers reduced during the journey. Somehow this is a picture of the 2nd coming though I am not clear on how yet. I think it may be related to the 10 virgins - only 5 of who go in to the marriage supper - the ones having oil in their vessels. This would be the born again believers, the temple (tabernacles) in whom the Lord dwells by His Spirit - the true Church and Body of Christ - His Bride.
The feasts thus give the picture for Israel's redemption and judgment for those who rejected it. These things can only apply to them in the 1st century since the Church is now safely inhabiting the New Jerusalem which is above. Therefore most of Revelation is not about or given to the Church today who is waiting for the Lord's return. Instead Revelation is providing us the understanding for the spiritual antitype which symbols were established in the earthly events which occurred in the 1st century fulfilling the type which they memorialized.
Satan's little season is all we need be concerned with which the NT gives us adequate instruction for how to deal with: by holding fast to the faith, once delivered to the saints, and continuing to walk in love until the Lord returns.
For greater is He who is in you than he who is in the world!