Got my healthcare packet 6 weeks before my 1 year mark. It was about a 120 page book, a few pamphlets, and about a dozen supplemental pages. Basically if you don't have dependents and don't want extra life/disability insurance you don't even have to do anything it starts automatically.
However if you have health issues I advise you to add the extra life insurance right away because if you don't sign up by your one year mark you will have to get a doctor to qualify you with whatever paperwork that entails.