The Dave Ramsey 6 months to a year is not correct. Bad credit stay on for 7 years, but an account in good standing when closed will show for 10 yearsshow for 10 years. When I check my own credit report, I see pages of accounts long closed.
I am curious how you'd plan to rent a car or reserve a hotel room. These are the 2 things that come to mind which are pretty annoying to do without a credit card.
Edit - I added a link to back up my 10 year claim. And I shake my head at the downvote with no comment. Even though I was not critical of The David.