The Kholinar riots were initiated as a consequence of the decadence of the Alethi lighteyed leadership, in general, and Queen Aesudan Kholin, in particular. This decadence was denounced by the Ardent Pai, who was executed the following morning. By that day's evening, the riots had begun.
Dalinar gets word via spanreed that Kholinar is in revolt when reaching out to other kingdoms to warn them about the Everstorm on the first day in Urithiru. As he would have been using spanreeds during the expedition, and he hadn’t heard of any revolt prior to day fourteen, it's probable that Kholinar’s revolt happened on the same day of the battle on the Shattered Plains.