Living with a strick schedule

Recently I have noticed that I live on this rediculous schedule. If anything throws it off I am completly thrown for a loop. I feel like everything in my day has to be done at a certain time or in a certain time frame. I literally do the same thing nearly everyday.
My father is a truck driver and has been for years. He decided he was in the area and wanted to stop for dinner. Needless to say, I was completely unprepared. He of course wanted dinner, but I was worried that I didnt have enough. I only cook just enough, cause my family doesnt like leftovers??go figure. Plus, I had to wait for him to get here to eat, which was not untill like 7:00. We eat at 6:00 everynight, so that was the first thing. Then, I had to of course give the girls a bath, should have been done by 7, but never got done till like 8:30. And then Emma never got to bed till 9 which is an hour past her bed time. Which makes it very hard for me in the morning. She is a girl that needs her sleep. So after all of that and all the lateness, my father, God love him, never left here till like 11:30. My day starts at 5:15 am every morning so the next morning we were all so exhausted. I know it sounds like something simple and little to most people, but I keep a strict scedule for many reasons and mostly its to avoid meltdowns from my husband and kids. Needless to say we are all still trying to get caught up from the glitch in our schedule. SO after all of this my question is HOW? How do I become a more flexible person and not be stuck in such a routine? And How do I cope with it all when my schedule is thrown off?