I also wait til we get home in the evening to feed dinner, last night we trained at 6(hour+ drive) and he didn't eat dinner til almost 10 pm.
The morning meal is fairly important, my dog will barf bile if his gut is empty for too long. So I will give a small portion before we leave in the morning and then he gets a bit of food during tracking. I will give another small portion after we do obedience during the break before protection. I feed raw so I don't worry too much about bloating(though I know raw fed dogs can and do bloat!)
If you are doing running and jumping with a 1 yr old for an hour, I would give a very small meal either very early in the morning or an hour or two after training.
I would ask your instructor or others who are training in the sport that you are what they do.