SEO is lots of things, not just the underhand (eg keyword stuffing) nonsense.

Make sure that whatever site you put up HAS GOOD CONTENT, is accessible, uses semantic HTML, and some sort of metadata such as schema.org to help ensure that the search engines can show you for the right queries.

Doing SEO last is like washing your hands last or thinking about security last. It's not hard to do the basic good robust everyday stuff as you go along, and not doing it will likely leave you invisible or worse, IMHO.