Mine go on at the end. Overlap the first 2 turns and then insert the whip. Go 2 more turns under pressure and the cut thread and put in the whip and pull back through. Apply with a bit more thread tension than the guidewrap thread and it will not pop off.
If you want a thinner band, apply the whip to the blank before your first wrap. Go around twice and as you approach the second time to cross the loose piece of thread, cut it close and then go over the loose thread before it has time to unravel. Go one more time and then cut and pull the whip back under the threads. Cut it very close and then use your fingernail to push the tag end piece back under the threads.
Now, if you want a single turn trim band, you would do this one in within the wrap, not at the end. Start your wrap and after the third or 4th revolution, delicately insert a piece of contrasting color thread under the wrap. Let go of the loose thread and keep it away from the tension thread. Go 2 or 3 more turns with the wrap thread and then take the trim thread and make one revolution with that. Then overlap the tension thread and then continue your guidewrap.
Hope this helps.
Kevin