Application was done 4/14/18 my birthday is 7/12/56.my confirmation letter says first payment is 9/19/18, why the two month wait?
You must be at least age 62 for a full month in order to be eligible for Social Security retirement benefits (https://www.ssa.gov/OP_Home%2Fhandbook/handbook.03/handbook-0301.html). So in your case, this August is the first month that you could claim benefits. And, Social Security benefits are paid in the month following the month for which payment is due, hence your first payment is scheduled for September.
In most cases Social Security benefits are paid on either the 2nd, 3rd or 4th Wednesday of a month depending on your birthdate. Since you were born in the middle 10 days of the month, your regular payment date will be on the 3rd Wednesday of each month.