I don't think anything you have done, which is outside of the standard C41 standard, is, or will be, an issue.
I have never seen a lab that does C41 with a pre-wash, nor have I ever seen a mini-lab with a pre-wash incorporated. I myself have never done a pre-wash with the C41 process. That does not mean doing a pre-wash is incorrect, it just means the vast majority of C41 processed on the planet does not have that happen. Don't worry about it, if it works for you, just keep on doing it.
The stop bath will not really change anything, it just stops the development instantly; well, within 2 seconds of it hitting the film anyway.
If you look back at your C41 negatives, going back years if you can, you will invariably see differing variations of the mask colour, "it's what it is," comes to mind.
Looking forward to seeing some results, hopefully, they'll be positive............................
Mick.