Welcome to the Q&A Forum

So glad if the links were helpful, James

Hey James! Joy Hawkins wrote an excellent post on this topic last year. Check it out: http://searchengineland.com/business-owners-guide-moving-office-234671 Should be just what the doctor ordered!

it is not too late, but of course you must to do it correctly

It should be fine - your site is built in wordpress, and you can just change your wordpress setting to show as www. instead of without the www - make sure your site is configured to 301 redirect to the www version, and you should be fine as far as the search engines are concerned.