According to Richard Brownlee, Gray Ghosts of the Confederacy, page 56, the Walker incident happened December 10, 1860. Not sure about where you read my notes, but Quantrill and his men had their first skirmish at Blue Springs, Jackson County, MO, February 1st or 2nd 1862. Again the reference is Richard Brownlee page 59. I hope this helps.
Rose Mary Lankford