You’re eligible to receive a progressive bonus every 4 hours! There’s a progress bar at the bottom of the game lobby which indicates how much time is left until your next bonus will be available and how many more bonuses you need to collect to be eligible for the Mega Wheel Bonus.
These bonuses grow as you level up! So play hard and progress as much as possible in the game.
Also, make sure to log in every 4 hours to take advantage of these bonuses as much as possible.