C I Schofield’s KJV Reference Bible, which was the “gold standard” when I was in that belief, was first published in 1909. Darby and the Plymouth Brethern are others prominent in early dispensationalism; but my memory is lacking on much detail. I know 1909 because I have MY copy of the Schofield Bible at hand.
"If ye have heard of the DISPENSATION OF THE GRACE OF GOD which is GIVEN ME TO YOU-WARD; how that by revelation He made known unto ME, the mystery..."(Eph. 3:2,3,5,6,9).
Paul goes back a little further than Darby and the Plymouth Brethern. Or Schofield.
The "Rightly Dividing" indeed fissiparation, certainly blossomed among these folks, and in a hurry too. I think maybe the most exotic blossom might be the Jehovah's Witnesses who, to me, are the prime example of what can happen when you excise Scripture from its proper context.
Anyway, thanks for the info.