6:27

6:28

6:29

6:30

I subtracted 6:28 & 6:27 then 6:29 & 6:28 then 6:30 & 6:29. then added the numbers together.then divided them  by 3 to get 34488.6. then  by 60 to get hours which is 574.81  by  24 to get the days which are 23.95046297.I believe that the closer you get to 25 billion the faster it gets so I believe it will end on March 26 at  7:40 becuse it will get faster as it gets closer.
More info at http://threeacts.mrmeyer.com/25billionapps/