What is my first eligible retirement date

Bear with me as I try to explain the answer, which is YES, you can retire June 30, 2025, with your 20 years as long as you are age 50 or older.
OK, here goes. In the HR world, all months have 30 days and when subtracting one date from another, you always add one to the last day to receive credit for that day unless you are retiring on the 31st, in which case the 1 has already been added (remember all months have 30 days). Then to be sure it is as confusing as possible, if you retire the last day of February, you would add either 2 or 3 days, again, because all months have 30 days plus 1 for the last day.
Example: Retirement date is 2025 – 06 – 30 + 1 = 31. Subtract from that 2005 – 07 – 01 and you have 19 years 11 months and 30 days. Thirty days equals 1 month so add that one month to the 11 months and you get 12 months, 12 months equals a year now add that to the 19 years you have a 20 year career.
YES, that is exactly how we do math in the HR world.