Should I add the Acknowledgement in the pre-final version of a (PhD) thesis for proofreading already? Or wait after I got the feedback from my supervisor?
Do whatever you want -- it doesn't matter unless you plan on saying something negative about anyone in there (which I would advise against :-) ) nobody cares what is or isn't in the pre-final version.
On a broader level, the fact that you worry about this sort of issue and take the time to write a StackExchange question about it means that you need to learn to separate the issues in your life that matter and those that don't. There are plenty of things that deserve your brain power. This is not one of them, but spending time and energy on it means that the things that deserve it do not receive it.