Whether you are in a parallel universe or the same universe is irrelevant. The concept here is that time simply a measurement of change no matter how you chose to represent it. Let's use a simple example of a series of dots represent change ie the passage of time.
0..............................1.......2.......... .................3................................ .................................................. ........................4
Let's now say that 1is Cable's birth in 616. 2 is Jean and Cyclops being sent to the future and raising Cable. 3 is Jean and Cyclops being sent back to 2. 4 is Cable being sent back in time to 0 before his birth.
The dots that represent the measurement of change happen. It doesn't matter if make them linear, make them run parallel or arrange them in a circle. The point is change is happening. So when Jean and Cyke time travel back to point 2, they still had the changes that took place between 2 and 3. Likewise, when Cable went from 4 back to 0, all the changes that happened to him from his birth at 1 to the point in 4 still happened. The dots are not altered by act of time travel. What can happen is the dots can be altered once the time traveler arrives in the past and if that is within the same universe then it can create paradoxes or change history or if that is within a parallel universe, it can create a divergence from the original timeline. However, the key again is that nothing that happened prior to the time travel is altered by the initial act of time travel. Those dots still happened and the measurement of change ie time still occurred.