I also have a border terrier and an instructor. I tell my students to enter both the first trial. Instinct is a time for you to get used to being in the ring and not to fail. It also is a time to reward your dog at the beginning of an event to what they are in there to hunt for. If they get the game and have prey drive, it is then a waste of time to keep entering them for the rest of the event. It becomes boring with the tubes right out in the open. I would enter them in novice. It isn’t rushing a dog with game and drive. It gives them and you another chance to have fun. Just my two cents with the experience of seeing my students at trials and judging many events.