The best time to buy a plan is between your mid-50s and your mid-60s when you are still relatively healthy and can qualify for a policy. This is the so-called "sweet spot." Purchasing a policy within this time frame will help ensure that you don’t pay too much for a policy, which is likely to happen if you purchase a policy in your 30s or even 40s and don’t need coverage until you are in your 80s.