Your need to make a final choice is not normally an issue until you have thousands of hours of flight experience, and by then you'll either have a job you enjoy or know which areas of aviation you want to avoid. Initially, you should pursue any job opportunity that helps you build those valuable pilot-in-command and second-in-command hours.
Many pilots often fall into their final aviation career by accident. One airline pilot I worked with found himself out of a job when his airline went on strike more than 20 years ago. Hired by a freight company, he soon decided that passengers and flight attendants were not to his liking, and he decided to remain with the cargo carrier. To this day, he is still a fan of nonpassenger aviation.
What you will need is flying experience, the more varied the better. Rather than worrying about what your ultimate job looks like, you should be gaining flight experience in whatever job gives you the best opportunity to build quality flight time.
Choosing now is fine, but don't set your heart on it. Be flexible. Your goal is to fly. The when, where, and how are negotiable and will depend on your training, networking, location, timing, job opportunities, the economy, and many other factors.
Now is the time to network and ask questions of all professional pilots you meet (that's why line service is such a great meet-and-greet position) to see why they chose the job they did. Would they do it differently if that had to do it over again?
Plan now your future aviation goals, but don't worry about the need to make a final decision when you're really at the sampling stage. Enjoy the ride and be sure you don't limit your options by taking unnecessary chances that could damage your candidacy later.
Capt. Karen Kahn is the author of Flight Guide for Success: Tips and Tactics for the Aspiring Airline Pilot and a career counselor (www.AviationCareerCounseling.com). A Master CFI and 30-year airline pilot, she flies the Boeing 757/767 for a major U.S. carrier.