You can adjust Pikatimer using the adjacent delays and hope that brings you closer. If, however, Pikatimer is bringing you +/- 5 of your delay, you're best off leaving Pikatimer alone unless you see yourself hitting the same adjacent delay twice. Pikatimer isn't perfect. It's best to just keep trying. This is part of doing RNG. I have spent more than a day on some pokemon because of swinging delays.