I believe that the 1260 days are referring to the time frame of 538-1798 A.D. The "remnant of her seed" are the [ true ] Christians that the Holy Roman Empire persecuted during the Dark Ages.
You somehow mysterously make 1260 days into 1260 years! lol
The time frame of three and a half years in the Revelation of Jesus Christ is stated in three ways, 42 months (Rev 11v2, 13v5), time, times (dual) and half a time (Rev 12v14 with Dan 7v25, 12v7) and 1260 days (Rev 11v3, 12v6)!
There are no long periods of time mentioned in Rev 4v1 to 19v21. The only other periods of time mentioned besides the 3½ years, are short periods of time. Rev 6v11, 8v1, 9v5,10,15, 11v14, 18v9,17. It is total folly to make a day mean a year, as you have done, for where God means a year, as in Rev 20v2-7, He says so. God gave this period of 3½ years in three ways, days, months and years, to convince us that He means just what He has said.
Those who make 2Peter 3v8, Numb 14v34 and Ezek 4v6, the excuse for a year for day theory, are twisting the Scriptures; and disqualify themselves from being taken as serious prophetic students; and prove that they cannot “correctly analyse the Word of truth.” 2Tim 2v15. These absurd theories make prophetic dating quite meaningless. In Num 14v34 and Ezek 4v6, the days are literal days, and the years are literal years, they are certainly not a principle of prophetic interpretation. In Numb 14v34, God states a fact of judgement, not a principle of prophetic interpretation; the 40 days of unbelieving spying out of Canaan, received a judicial sentence of 40 years of wandering in the wilderness, and God's breach of promise. Num 13v17 to 14v45. In Ezek 4v6, Ezekiel's symbolic act brought to public notice the 430 years of past sin for which judgement was to come, and in 2Peter 3v8 Peter compares the many years of God's longsuffering with His tremendous judgements on the day of the Lord.
People use this method of interpretation, so that they can twist the facts, for a symbolically interpreted prophecy, can be made to mean almost any thing they desire. Who decides which dates are symbolic and which are literal? We should accept the time periods God has given to us and not tamper with them. How do you explain the “half hour” of Rev 8v1, and the “five months” and “thirteen months” of Rev 9v5,10,15? If we fail to interpret Scripture dates literally, we end in utter darkness.
Also consider the dire warning the Lord Jesus states in Rev 22v18,19!