I have been looking at tutorials and searching the web for days trying to find an After Effects expression that will help me to count down from a specific date, similar to what this site does:

https://www.timeanddate.com/countdown/generic?iso=20161118T00&p0=155&font=c...
I want to do it in After Effects because I need to export it in MP4. I have already seen something similar to what I need here:

https://www.facebook.com/BuzzFeed/videos/10155300775200329/
If anyone could help me with an expression or point me to a plug in or resource that could assist me in accomplishing this I would greatly appreciate it. I am very new at expressions and I've been trying to modify some I've found with hours and minutes only but I can't figure it out to get days and hours too. Thank you in advance for any insight!!