Sunrise - from earth - sun position or when sun rays reaches earth?
It's when we see the Sun's rays and includes refraction. It also is the moment we see the first glimpse of the sun. Think of it this way: we humans need to know sunrise and sunset for our human activities; the fact that the sun is about eight light-minutes away doesn't concern us, doesn't affect the things we do. BTW, this is also true of solstices and equinoxes.