My first fast was 1 week followed by 1 week of juice only.
My wife's first fast was 1 week.
My friend's first fast was 2 weeks.
Many people say that they "just can't do it". With that attitude, you have just created a self-fulfilling prophecy.
Give yourself a little credit.
You need a good 2-3 days to get past the hunger pains (which is what scares most weak people from fasting in the first place) and enter a solid state of ketosis and healing.
A week long fast isn't too much to ask for the first time. Will it be easy? Maybe not. It depends on your condition. My first fast was hell. My wife's first fast was not bad at all, her tongue didn't even turn white.