Scenario:
Double Battle (Electivire/Zapdos vs whatever). Normal priority based on speed is Zapdos, Enemy 1, Enemy 2, Electivire. Round 1, Zapdos attacks first with Discharge, damages enemies, boosts Electivire's speed one stage. If Electivire's new speed is faster than Enemy 1 and 2, does its new priority become effective immediately, allowing it to attack before Enemy 1 and 2 during first round, or does the speed boost not really come into play until Round 2?