Hey Briguy,
Good work on the test race; sounds like your body handled it well and sustained through a long, easy session the next day.
The delayed muscle soreness certainly isn’t unusual but it can be different each time, and your hunch on protocol is correct: i would recommend avoiding any intensity or significant strength work until your quads feel supple again and aren’t sore. The pain/soreness indicates that recovery and healing are still happening, so further stress would not only hamper recovery, and the attempted gains from such a workout will be curtailed because the muscles aren’t ready for the load.
Bottom line: easy training until the soreness is gone, then you can hit it again.