Do I have to show up at a certain time?
You can take the lessons whenever you like and at your own pace. And since the course includes lifetime access there's no time limit, so you can re-watch lessons whenever you need.
That being said, I recommend blocking out time in your calendar as soon as you've joined the course to ensure you complete the lessons at your desired pace. For example, you might schedule 2 hours a week over 4 weeks.