Ah, Mark, you've hit upon the most delicate part of the art of mooching (cut-plugging): "The Bite". There aren't many of us cut-pluggers still around now, not like the '80's when just about everyone was cut-plugging. Pulling hardware seems to be the way to go.
Here are a few theories on how a King (a Spring as we locals call them) takes the bait.
Bite One: a Spring approaching its spawning territory, can have one or two things on its mind: food or ***. Maybe both. They are usually slow moving, fat, sometimes lazy and can have an empty stomach. A Spring may take your bait, mash it around in its mouth and spit it out. Perhaps it thinks the herring is competition (just kidding). You, in the boat get a mixed signal: usually a fast rod tip twitch of from one to two inches. You will wonder in amazement how a herring could be so smashed, just pulverized, without a hook touching the bugger.
Bite Two: a Spring will take your bait, usually when you're looking at your other rod tip, and move forward just a few feet taking up the weight of your sinker so that your rod tip will staighten (a very good sign). When your eyes and mind adjust to what's happened, gently pick up you rod, crank down smoothly and quickly until your rod tip is buried in the water. Set the hook. Chances are it's swallowed the bait.
Bite Three: a Chinook who hits your bait and runs will not give you time to "pass, kick or fumble". Just hang on.
Thanks for asking about giving slack line at the bite. It's usually your opportunity for the Spring to get a better "grip" on the bait and a time for you to start an "Our Father or a Hail Mary".
"The Bite" is the most important part of mooching and you'll remember it for the rest of your life.
Spring Drifter