To be more precise, let $P$ denote the position where the Earth is at the time this post is submitted. Assume our coordinate system is such that this point is fixed in space and the rest of the universe is expanding away from it. Therefore, by the time you are reading this, Earth will have already left $P$ due to it orbiting the Sun and the rotation of the Milky Way etc. However, this distance is negligible on cosmological length scales.
So more precisely, my question is: which objects were the furthest away at the time they sent/emitted light which have reached $P$?
I believe the cosmic microwave background (CMB) radiation is the oldest light to reach $P$. The universe was approximately 379,000 years old when the particles emitted the light that makes up the CMB. However, the universe was much smaller (or denser if the universe is infinite) at the time that light was emitted. Therefore, $P$ and the particles that emitted the CMB light, were actually quite close together (on cosmological length scales)? It depends on how much the universe expanded in the first 379,000 years, but I'm not sure what to 'google' to find that out.
Therefore, the most distance light (at the time the light was emitted) is not the oldest light?