I got my board Results in May as well. Last day of AD was 31 Dec.
Big advice. Make your last day of AD on 30 Dec. Vice 31 Dec. reason is the VA. If you go out on 30 Dec you get your first VA check on 01 Feb. if you retire on 31 Dec then you get your first check on 01 Mar! I found out the hard way.
Remember your date of separation/Retirement is a DUTY DAY - you are not separated/retired from service until the NEXT day, while the VA deems you disabled on the first day of the first full month of separation (+1 from separation month). If you retire on the last day of the month (31 DEC) you are not separated until the 1st of the next month (JAN is month of Separation) and you are disabled on the first of the NEXT month (1 FEB), you will be paid on the 1st day of the third month (1 MAR). If you separate a couple days early in the month (30DEC) then your next day you will be disabled in the same month(31 DEC), resulting in the next month as your first full month (1 JAN) of disability resulting in compensation on the 2nd month after separation (1FEB). It seems ridiculous, but it is just the way it works, you can not be in service and disabled at the same, that's while VA disability lags by 1 month after separation and then pay lags by one month because they pay you for compensation of the time you were disabled, not ahead of time.
Similar to how working for pay is done, you work 40 hours, then your pay comes after you have worked, not before.
These dates and days are not the whole story, but the easiest way I can describe it to you. The actual explanation on the VA website takes pages to copy paste.