The acurate flight time at which you will see the sun is found by integrating the aircaft ground speed, the earth angular speed at the latitude flown at the time of local sunrise and the date (season, that is the earth inclination relative to its orbit plane). We used to do that kind of of navigation execise at school, before the digital computers, JAR-FCL and PPRUNE to do the homework for us
I won't give the formula and its solution here, just in case you are one of those trying to skip his homework, but if the question is genuine, then you should see first glimpse of rising sun on the forward right side of the aircraft around 65 deg East, and that would be around 2 AM London time, 10 AM Hong Kong time.