I would like to know how you deal with Events etc. that require you to change your plans and so also your to do list or completely change your timetable?

Something that was hard for me to learn is that things don’t always go the way you want them to and for that not to ruin your day you have to be little flexible. I honestly still learning this.
If your plans change think about the top tasks of your to-do list, the ones that must be done and move the rest to another day.

I get the most important things done and leave the aspirational things for later. So I make sure I take my meds, for example, because I need those. I also make some concessions. If I can't take 10 minutes to meditate, I take one or two minutes or go into my stretching/yoga and drop into as much meditation as I can while I do it and multitask. I've also set up some goals at separate parts of the day. So I have a yoga task in the afternoon and at night and meditation 3 times a day. The redundancy means that at some point during the day I'm going to get to meditate and do yoga at least once. And if I can't get any of the aspirational stuff done, I accept it, move on, and just know that I didn't have time for it that day. Sometimes playing an 8 hour board game with friends is more nourishing for my soul than the yoga and meditation.