A tip for buying extra shades is to buy 1 cone and wind off onto 2 or 3 machine bobbins if you want a match for a particular garment. Also have a light grey and a dark grey and maybe an off white or cream. You can mix shades as well say a darker for the upper looper thread, that is normally on top side, (think of a turned up hem on a skirt or trouser) and one that isn't quite such a good match for the under looper.
I generally like my overlocker threads to match, so another vote for buying 4 reels of Moon thread. BTW, you can also get larger cones of Moon thread.
Winding from a cone onto a machine bobbin is OK for needle threads (assuming your bobbins will fit onto the overlocker's spool pins) but not practical for the looper threads as they use so much more thread. As a minimum you need two cones of any colour.
What’s the first make?