Do not take it for granted that your credit report is all right. Old skeletons and errors can cause havoc when applying for a mortgage. It is a good Idea. Do not think of credit-reporting companies as infallible. Indeed, they can be very fallible.
Mistakes can and do occur, and they often take time, sometimes many months, to correct.
That is why checking on your credit early is a good idea. Errors can almost always be cleared up, but it may not be easy. And it could take several months or, in rare cases much longer. The process involves informing the credit-reporting agency of the error and then often going back to the original lender who reported bad credit and getting it to remove its report. The only thing worse than bad credit, is no credit.