I got two of those rock chips in my Eclipse windshield in month (last summer). One was repaired professionally (if memory serves ~$40) the other I repaired with a kit from Advance Auto (if memory serves ~$10). The home repair looks MUCH better and they are holding up the same so far.
I only took the one in to be professionally done because I thought it would be completely invisible. I was wrong.
I strongly suggest you try the repair immediately because the repair will keep the cracks from spreading.