As you complete tasks and level up in the game, you will unlock the shelter's calendar.
Once you do so, you can press it to access the Daily Bonus; this feature will allow you to claim a daily prize when you start playing.
Its prizes will be sorted into seven days; each day will have a prize assigned to it and claiming it will release the next day's prize. Please note that if you fail to do so, you will start again from day one.
As soon as you acquire them, prizes will improve until you reach the seventh day, when you will get a pet. When you do so, the process will start again from the beginning and the seventh day's prize will be a pack of gems, among other items.