Check codes, if you have a code 51, the timing will jump when you are trying to change it. Secondly, you should make sure you have no codes before setting timing. If you have any, fix them. If you have the largest boost leak in the world, fix your codes first, then go after that. Codes are a way for the ECU to tell you what is going on and what is not working properly.
I know about the timing jumping since it happened to me. Make sure you have no codes, especially 51, when setting your timing and also that your car is fully warmed up to operating temperature. It should idle at around 650RPM when it is fully warmed up.
Make sure you jump the terminals as well before checking timing.