Ah, we are not doing the same thing at all.
I thread one long thread on a needle and double it, making a large knot to keep the pearls from sliding off. That is how I have 2 strands-- because it's doubled thread.
1. I string on 4 pearls without knotting, and slide them down almost as far as the large knot. (It's easier to trim the knot end later if the pearls don't go all the way to the knot; you want a few inches to grab and hold while you trim it.)
2. I string on the gimp, and the clasp, and slide them down to where the pearls are.
3. Then I double back through the pearl that was last to be strung on, which now becomes the pearl that is next to the clasp. I snug up the gimp with the clasp centered in it.
4. I make overhand knots between the first and 2nd pearl, between the 2nd and 3rd pearl, and between the 3rd and 4th pearl. Because these pearls are already on a doubled thread, the overhand knot is made over that thread. These end-pearl knots will thus be somewhat larger than knots made later.
I seat and tighten the knot by pulling the 2 threads apart.
5. When I get to the 4th pearl, I pass the needle through it but don't make a knot just yet. I cut off the tail with the big initial knot, thus hiding the tail in the 4th pearl. Then I make an overhand knot and carry on, making a knot after each pearl.
6. When I get to the last 4 pearls, I string them all on without knotting. String on the gimp, the clasp, and back through the end pearl, snuging up the thread and the gimp.
7. Make a knot between each of the end 3 pearls again.
8. Pass the thread through the 4th pearl from the end, do not knot this time-- just cut off the thread.
Is is clear?