When should I create a Common App account?

I’m only a freshman, but I would like to see how the Common App works. Can I create an account and fiddle around, or is it too early?

You can create a test account.

If you have extra free time I guess you can look around, but you can definitely wait until end of junior, beginning of senior year.

You can create one any time but the the particular common app that will apply to you is the one that appears about August 1 just before your senior year begins.