Without knowing exactly how to tell otherwise, it seems as though my first attempt at canning was successful.
Here's most of what I used:
I boiled the watery kumquat mixture for 45 minutes. I added pectin and sugar. I brought the mixture to 220 degrees (the gel stage). I sterilized the jars and lids in boiling water. I added the hot, gooey mixture to the sterilized jars. I twisted the lids on so they were "finger-tight," as instructed. I boiled the filled jars for 15 minutes each:
I removed them and let them cool, and then...
That sound of snapping-lids-as-a-vacuum-seal-was-formed. Or as I might call it from now on: An Angel Snapping. What a glorious sound!
This canning experiment feels like a big success based on that sound alone. Even though I know I added the pectin at probably the wrong stage. Also, I just boiled the jars and lids - I didn't truly sterilize them. I don't think? I don't know! Basically, what I learned is that I don't know enough about canning and I want to learn more.
Now I just wait for everything to set - 24 hours without any movement of the jars - and... Presto! Kumquat marmalade! Hopefully...
I'll know in the morning.