>>18720541See pic related for breeding
As far as I know, it doesn't matter when you EV train. What I do is throw a power item on whatever I'm training, and have a Tropius with Sweet Scent, Fly, EQ and Razor Leaf in front of my party for Horde grinding. If you have good luck (right horde encounters, no rain) You can max out the desired EVs in ~20 minutes.