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.
3. Eligibility. You must claim the new State Pension if you reach State Pension age on or after 6 April 2016. The earliest you can get the basic State Pension is when you reach State Pension age. To get the full basic State Pension you need a total of 30 qualifying years of National Insurance contributions or credits.