You will need to complete all three challenges for every day of the month. You can start this on any date, as long as you make sure to finish it on the last day of the month.
For the hard and expert challenges you can go to youtube.com and in the search bar type in the name of the game and the date of the challenge you want to see the solution for, such as "Microsoft mahjong September 24 2016". I am just using that date as an example, because it's the day I wrote this solution.
There are a few people that will upload the hard and/or expert challenge from each day so you shouldn't have a problem finding the help you need for the harder puzzles.