How do I adjust my workouts for this week only, schedule ahead for the next week, or add an extra day of workouts?

Currently, there is not a way for you to only adjust one day of your workout calendar or add in an extra day. When you generate a workout program, it will be consistent across the weeks for the number of days you selected, e.g. if you select a 3-day split, it will only be for 3 days every single week.