You stand a good chance of making it to 20 years. Read some of the posts on this forum. You will begin to recognize some of the forum members who have been around for a while. They have solid advice.
I am in a similar boat. I have to make it to Jan/Feb 2020 as well. Remember this! Appeal, appeal, appeal. Appeal at every turn. Do the IMR, then the appeal, then the FPEB and if required do a VARR (VA Ratings Reconsideration). What post are you on? Also, go see MEB legal now if you have not already done so. They have been invaluable to me.
You don't have to submit the COAD until your DA 199 comes back. Have you signed your NARSUM yet? If not, like I said, do an IMR then appeal. Who did you're exams? VA or QTC? What was the quality of the exams? You can try and contest that as well. Bottom line, do everything in your control to delay.
When your NARSUM moves from the MEB to the iPEB, it then goes to the VA in Seattle. Right now that is taking a few months. That is when your 199 comes back