I normally spend a great deal of time identifying and then contacting new candidates. These are known as "passive" candidates . . . the ones not actively looking for a new job. These are the candidates that recruiters strive to deliver, and employers generally don't reach. They need to be "recruited". They don't spend their time looking for a new job and they don't respond to job postings.
These passive candidates are generally a company's top performers. They're hard working, loyal and spend their working hours contributing to their employer. This does not mean that they wouldn't be interested in hearing more about opportunities that have the potential to be clearly better than what they're currently doing. I love the part of my job when I introduce a new opportunity and the passive candidate says "Yes, I want to hear more . . ."
It's remarkable to me how few people have a current resume, and almost no marketing executives or account service professionals have what I'll call a "portfolio". It's a portfolio that's an assembly of documents, printed materials, tearsheets, spreadsheets, briefs, branding rationales or other writing samples, testimonials and recommendations, etc.. When I ask a client side marketer if they have a "portfolio", I often get an indignant response like "I'm not a creative". Not being "a creative" is not an excuse for never having an assembly of the things you have accomplished successfully throughout your career. Many, if not most marketers I know do identify themselves as being "creative".
I've found, and some clients agree that a well presented portfolio can be the difference between getting hired, for that exciting new opportunity or not. It can be what explains your previous contributions so clearly and effectively, that a new employer "gets it", and can't wait to get you working on their team. Portfolios can illustrate your accomplishments so effectively, that the compensation package is increased.
In short, there's no good reason not to have one . . . No matter how much experience you have, now is always the best time to start. Your portfolio doesn't have to be terribly complex. Some of the most effective account service/marketing portfolios are from pros with less than 10 years of experience. They understand the value of "case studies". A clearly laid out case study can be simple, yet it tells a marketing story beautifully. Its value is further enhanced, because someone who presents case studies clearly understands what their job is really all about, and what success for the client really means.