The best advice I've heard is that two birds will aim for the trainer, then the next will aim for you. I think it might be different depending who goes around the corner first, but it proved invaluable.
Chocobo Racing was the most difficult of the Sigil challenges for me, as well. On my latest save it took me a couple of hours. After I got the 0 seconds I did the race again to get that woman away from the Celestial Weapon opening, and got 0 seconds again. Now that's frustrating.