Jude 6 and 2 Pet. 2:4 refer to an historical fall of these angels as a class. "The angels that sinned" were all dealt with together. I would be inclined to think this is the general view of Reformed theologians.
Helpful. I tend to agree. I went home and looked up where I had remembered reading it and lo and behold,
@Phil D. was right. It was Edwards and his Miscellanies.
To be precise, it was really Edwards quoted in Beeke and Jones:
(3) God's establishment of elect angels in righteousness.
... Jonathan Edwards devoted a dozen of his "Miscellanies" to the confirmation of elect angels. He saw confirmation as a progressive work that began with "the terrible destruction that God brought upon the angels that fell," and continued with the "experience of the elect angels in their own happiness in standing", particularly in Christ's work of redemption (Eph. 3:10; 1 Tim. 3:16; 1 Peter 1:12). That ended the time of probation for the angels, who received the full and certain confirmation of eternal life when Christ ascended into heaven.
- Miscellanies 442 and 515 from The Works of Jonathan Edwards, quoted in Beeke, Joel and Jones, Mark. "The Puritans on Angels". A Puritan Theology, p. 184.
I will now try to track Edwards' thinking.
If P1: God makes known or reveals unto the apostles and prophets (v. 5) by the Spirit ... to the intent that now
unto the principalities and powers in heavenly places might be known by the church the manifold wisdom of God", (Eph. 3:10)
and if P2: "great is the mystery of godliness: God was manifest in the flesh, justified in the Spirit,
seen of angels, preached unto the Gentiles, believed on in the world, received up into glory." (1 Tim. 3:16)
and if P3: "unto us they did minister the things, which are now reported unto you by them that have preached the gospel unto you with the Holy Ghost sent down from heaven;
which things the angels desire to look into." (1 Peter 1:12)
then it can be concluded: C1 - God established the elect angels in holiness and happiness (WLC Q. 19) by making known
by the church his manifold wisdom
to the elect angels in heaven (Eph. 3:10)
C2: The Incarnation including all events from birth to death to resurrection to ascension to mediation is seen by angels with great desire to look into because it stands to reason that their election is connected with the work of Christ (WCF/1689 3.3) in a different way than the work of Christ and the Spirit births new life into man (logical deduction since it is axiomatic that elect angels are not totally depraved by original sin having had no federal head that fell).
I don't think anything in here warrants any idea that after the fall of Adam and before the Incarnation there is any indicator that a seemingly-elect angel would fall into sin and be exposed as reprobate. (eg, at a moment of crisis such as Gethsemane).
Even if one accepts Edwards' hypothetical timeline of the ages-long probation period for elect angels that ended at the Ascension, that premise of more falling angels during those ages would be extraneous and have no Biblical warrant that I can see using responsible hermeneutics.
Thanks everyone; I simply was overpreparing for an upcoming Sunday school lesson on 1689 3.3. God bless you all