Yes. It is common mistake - running too fast. You need to find your pace. Do not worry about speed, it will come. At the beginning your main goal is to complete the day and feel good about it.
Since first three weeks are the same daily (you can peek at them in the app, or google "C25K" for text schedule) you can move on o the next day. But it is OK to repeat days or weeks if you want to be more sure in your strength.