Monday Hour One

I’m brand new to time blocking my schedule for the week. I just started this week. I ended up getting sick on Tuesday and it threw off my entire schedule. I really wanted to stick with it but also felt like I had to honor how I felt and get rest! I’m feeling frustrated that I was unable to stick to it and am also wondering in general does it take time to get used to being able to know how long things will take and realistically what can happen?