there is NO simple answer --
your situation is a bit different than someone else.
and where you live does matter -

the key is is do your homework early ..

this piece may help ..

Adding up the cost of Medicare

http://www.kiplinger.com/article/insurance/T039-C000-S002-when-to-sign-up-for-medicare-when-to-delay.html

Before you decide to sign up for Medicare or stay on an employer’s health plan, compare all the costs. Your employer’s coverage may be less expensive.

You don’t pay a premium for Medicare Part A, which covers hospitalization. But for Medicare Part B, which covers outpatient care, most people pay $104.90 per month. Single enrollees earning more than $85,000 and married enrollees filing jointly and earning more than $170,000 pay $146.90 to $335.70 per person per month.

Unless you have retiree health insurance, you’ll probably want a medigap policy to help cover co-payments and deductibles, and a Part D drug plan to cover prescription drugs. Part D averages $32 per person (plus a high-income surcharge that boosts premiums by $12.30 to $70.80 per person if income is above $85,000 for singles or $170,000 for couples). The most popular medigap policy, Plan F, has a median premium of $172 per month, according to Weiss Ratings.

Even without the high-income surcharges, your monthly costs to sign up for Part B, medigap insurance and Part D will run about $309 per person per month. You may be able to save money by buying a Medicare Advantage plan, which offers medical and drug coverage through a private network of providers; you pay the Part B premium plus an average Medicare Advantage premium of $33.90 a month.

You can get help with Medicare decisions from the Medicare Rights Center (www.medicarerights.org; 1-800-333-4114) or your local State Health Insurance Assistance Program (www.shiptalk.org; 1-800-633-4227).