Challenges are currently set for the following times:
Saturday: 4 PM CST
Monday: 10 PM CST
Wednesday: 10 PM CST
If you’re like me and are terrible with timezones, try this site http://www.worldtimezone.com/ . Type “Houston” into the “Search for City” bar near the top, find Houston Texas specifically on the following page, and with that you’ll be able to track what time 4 and 10 PM are for you!
Hope that made sense and helps!