I think that would be a terrible idea. If you still have 18-24 months of instructing, who knows what 18-24 months is going to do to this industry. The last thing you want is to be tied to Horizon and there be a 10X better deal for you to take with a different regional when you have your time.
If I were you I would just focus on getting my time and keeping up with the industry, but don't even think about committing yourself down to 1 regional yet. When you are about 6 months from getting your time, that is when I would be seriously considering which regional you would want to go to.