Actually, there is a much easier way to get to the correct glide path and hold it in the A10 and other modern A/C
The circle with the 3 lines stick out of it is the Flight Path indicator(FPI) and tells you where you are going, not where you are pointed (which is attitude).
So, adjust your attitude and descent rate to place the FPI on the end of the runway AND make sure the FPI is at the -3 degree point on the pitch ladder, NOW you are on a 3 degree glide path.