Let me start here. One must first decide on the sequence of Revelation and where everything fits in. This is how I see it. Then I'll take it from there. I do believe the beasts would have appeared during the breaking of the first three seals. Most things are already in place.
PetrW, I'm with you till "This is my basic view of the beasts of Rev 13 and 17. It is one and the same beast." Here I disagree. 1) Beast from sea. 2) Beast from earth. 3) Beast from abyss. Three beasts. And I compare "earth" of Revelation with Daniel's clay (in iron and clay part of image). Same substance. I think you "overthink" things. I go for Occam's Razor, i.e., simplest explanation is usually the best explanation.
Revelation 1:1-20 Prologue: The Day of the Lord
2:1-28 Messages to Ephesus, Smyrna, Pergamum and Thyatira congregation
3:1-22 Messages to Sardis, Philadelphia and Laodicea congregation
4:1-11 Beginning of the Lord’s day: God’s throne
12:1-17 Dragon and his angels expelled from heaven
13:1 Dragon on sea shore
13:2-18 Beast from the sea, Beast from the earth (the false prophet) and Image of the beast
17:8-14 Scarlet-colored wild beast
5:1-14 Scroll with seven seals
6:1-17 Breaking of the seals
7:1-8 Hundred and forty four thousand sealed
8:1-13 Seventh seal: Trumpet blast one to four
9:1-12 Trumpet blast five (1st Woe)
9:13-21 Trumpet blast six (2nd Woe)
11:3-6 Start of public ministry of two witnesses
10:1-11 Angel with feet on earth and sea
11:14-18 Trumpet blast seven (3rd Woe)
11:1 Measurement of earthly temple
11:2 Earthly temple courtyard trampled by nations
11:19 Heavenly tabernacle opened
15:1-8 Preparation of the plagues
16:1-11 Plague one to five
11:7-13 Death of the two witnesses
16:12-21 Plague six and seven
17:1-7 Identification of Babylon
17:15-18 Fall of Babylon
18:1-24 Mourning for Babylon
7:9-17 Great crowd survives Tribulation
14:6-13 Three final angelic warnings
19:1-10 Wedding of the Lamb
14:1-5 Hundred and forty four thousand
14:14-20 Summary of Armageddon
19:11-21 Armageddon
20:1-15 Christ’s millennial rule
21:1-27 During the millennium. New Jerusalem.
22:1-21 Epilogue