If you have to choose between one or the other I would travel now and build something later. You'll have more experience and meet new people while you are away. There's really no "right" answer here. You've stumbled upon microsm of life. If you truly value travel but this startup keeps you in one location then maybe it's a sign that it's not the best for you. As Jim Collins says "a once in a lifetime opportunity is fact, but not a reason".