I agree, you should definitely try a 7 day fast before shooting for the 30 days.
Just as a precaution and practice.
My first 3 juice fasts (started when I was like...18) were first 7 days, then 30 days, then 15 days. All went very well.
You're going to have so much fun with recipes. Some of them seem outlandish and untasty but you'd be surprised!
5 years later and I'm still amazing myself.
My boyfriend just got me the Breville pro juice fountain and I absolutely love it.