There are one set of twins that were born 87 days apart. One baby  was born on June 1, 2012. The next baby was born on August 26,  2012.
Not until you reach retirement age. Typically that's 65, though many pension plans allow you to start collecting early retirement benefits as early as age 55. If you decide to start receiving benefits before you reach full retirement age, the size of your monthly payout will be less than it would have been if you'd waited. Ask the folks who run your plan to create a simple table showing you how your payments will vary depending on when you start.
Retirement Planner: Benefits By Year Of Birth. Full retirement age is the age at which a person may first become entitled to full or unreduced retirement benefits. No matter what your full retirement age (also called normal retirement age) is, you may start receiving benefits as early as age 62 or as late as age 70. You can retire at any time between age 62 and full retirement age. However, if you start benefits early, your benefits are reduced a fraction of a percent for each month before your full retirement age.