Very few terriers are quick enough to outrun a rabbit once it bolts from a burrow – that’s very much the job of a running dog.
Most terriers however are more than capable of ambushing rabbits as they bolt from a hole, and it’s a job some cotton onto quickly, and they can make good rabbiting dogs.
My Jack Russell, Flea, catches a lot of rabbits at the mouth of the hole as they bolt but she has learnt this knack through a lot of experience.
What you must remember is that you don’t train a dog to hunt, this is something that comes instinctively.
By all means train your Border to be obedient but don’t ruin the dog by entering to quarry at too young an age.