Barry,
Shawn has given you excellent advice. You will benefit the most from constant exposure to aviation, and the people you will meet along the way, who might take an interest, and help you along. To be valuable as a test pilot, you will have to have thousands of hours of flying on appropriate aircraft types, and test experience on top of that. It won't be easy, but hey, everyone starts somewhere!
In the non-aviation job, you risk missing getting to know people who you will need to have mentor you later.
Most of the test pilots I know did not start their career with the intention of being a test pilot. Instead, after amassing considerable experience, they were called to the task.
Best of luck,
Pilot DAR