I'll try to give some of the pieces, without tying them together, and hopefully you will see some patterns:
1. Rev 12:1-2 has been determined to be celestial in nature.
2. Rev 12:3-4 also celestial by the use of 'another' in the text, indicating 'of the same type' since 'sign' is the same word
3. What if these signs (v1 and v3) were time markers, but the descriptions in v2 and v4 were allegorical? Looking closely at 12:2 can a stellar alignment really 'cry out in pain of labor'?
4. In v3 the sign is 'perceived' or 'seen' by John not 'appeared' as translated. The word 'appeared' is inferred. literally, the 12:3 verses could be read: "Also, another sign in heaven; behold..." The 12:1 verse could be read: "In heaven a great sign, a woman...."
5. If we did not see the dragon sign immediately near the Rev 12:1 sign, and looking at 12:3 "And another sign appeared in heaven" could indicate time elapsed since the first sign.
6. There is some speculation that the Draconids meteor shower should be very spectacular this year. If this aligns with 12:4, and if it is an allegorical sequence to 12:3 as 12:1 is to 12:2, then the 'appearance' of the Dragon sign would be before October 10, followed by the 'sweeping' of the Draconids (v4a) and then v4b.
7. We have no chronologically fixed time period dictated between the sign descriptions, but there is almost exactly 1 year from 9/23/17 to 10/10/18; as well as allegorical descriptions in 12:2 and 12:4
8. "Heaven" in v1 is οὐρανῷ (celestial heaven) in v3 is οὐρανῷ (celestial heaven) and in v4 is οὐρανοῦ (spelled differently - a different heaven, yet refers also to the celestial?). Could it be that the first two infer (imply parallels) to the abode of God; and the latter has no implication of that, but just the 'heavens'? See the strongs references for each spelling. They are used differently. The first appears to infer the dwelling place of God, the last does not?strong's 'heaven(s)'
9. Israel is often assigned the role of the woman in prophecy; 12:6.
10. If Rev 12 is an overview of the enture trib, then there seems to be a chronological sequence after 'the players' are introduced (v1 and v3):
a. the woman sign in 12:1 (9/23/17)
b. labor starts 12:2 (we have been seeing this in the news, i believe)
b. the dragon sign 12:3 (the blood moon in July?)
c. the sweeping of the stars in 12:4a (10/10/18)
d. the dragon standing before the woman in 12:4b (the peace deal?)
e. the birth of the male child 12:5a (israel's Aliyah?)
f. the catching up of the male child in 12:5b (Harpazo)
g. the fleeing of the woman into the wilderness 12:6 (mid-trib)
h. war breakout in Heaven 12:7
i. the victory of Michael and the Angels over the dragon 12:8
j. the casting out of the dragon with his angels 12:9 (Rev 9:1 angel with keys to the abyss?)