This can be completed in a single day with the following instructions:
1.Disconnect from wifi
2.boot up 2018
3.close 2018
4.boot up 2018 (the reason why we have to open and close the game offline is so it will fetch the console's time and not the server time)
5. do 1 challenge
6. close 2018
7. go to console settings and go up by 1 day
8. repeat
Doing this for "7" days will get it done!
Happy trophy Hunting!