“Im trying to get a handle on the speed of the radio signal vs. the speed of light.”
They’re exactly the same, because radio waves and light waves are just different frequencies of photons. All photons travel at the speed of light (in a vaccum), whether it’s visible light, microwaves, radio, infrared, etc.
All electromagnetic radiation, whether it is the dangerous gamma rays and X-rays, or visible light, or whether it's radio waves, etc., all propagate at the same speed; namely, the speed of light.
The range of these wavelengths (the range, not the radiation itself) is called the electromagnetic spectrum (see graphic below).
Visible light; i.e., the EM radiation our eyeballs can actually see, is only a very tiny slice out of the full range of electromagnetic wavelengths. When you look up at the night sky, it's like looking at the universe through a skinny straw. You see the visible light, but can't see all the other stuff. You're missing 99% of it.
That's why astronomers now have the gamma-ray telescope (the Fermi Gamma-ray space telescope), X-ray telescopes (a bunch of them), ultraviolet telescopes, etc., in space, so they can observe the universe in its full splendor.