A recommended method is to defeat 315 troops (or 630 if you go over 315 by accident), then report to Base #1, and then to the supply base when it gets pinged. Keep in mind that you have to wait until the multiples of 21, 35 and 63 are reported before moving from Base 1. When the supply base pings you can then head towards the supply base to finish the quest. You don't have to wait for him to finish talking. When you get close to 315 KOs, archers will be a target of choice since they don't move.
In case you happen to go over the recommended values, here are other multiples you can use for each request