First, you need to know your benefit and your spouse's benefit at full retirement age. You can obtain this information by looking up your benefit information on Social Security's website, www.ssa.gov.
Head on over to My Plan > Income
Open the Social Security section and press on the pencil icon to edit
(If you plan on receiving benefits) Press "Yes" when asked if you expect to receive Social Security benefits
Enter your benefit at full retirement age.
Select the age when you wish to claim your Social Security benefit. Your Benefit at Start Age (Pretax) will adjust, increasing if you delay past your Full Retirement Age and decreasing if you delay early.
Repeat the process for your spouse's benefit.