Photons don't experience time since they travel at the speed of light. Time passes slower the closer you get to the speed of light, until it stops at the speed of light. A photon that is part of the cosmic microwave background is indistinguishable from a photon created by my microwave oven unless you see where it's coming from.

If you are looking at the photon from an outside perspective, when fusion happens in the core, a lot of energy is released. The same photons from that reaction dont necessarily make it to the surface, rather get absorbed and remitted before taking 8 minutes to make it to Earth. That process of absorbtion and remitting from the core to the surface, on average takes about 100000 years.