The idea is pretty simple. I realize there is a timer on it when you finish a game, but other than that I do not know where to find one, so please correct me if I am missing something. What I propose is to put a timer on when your first win of the day is active somewhere in your own profile. Sort of like how the IP and EXP Bonuses work. Perhaps up at the top right by the IP # "Win of the day ready!". Either that or a time stamp on your match history so you know what time the last game took place. That's what I thought of on short notice and I'm sure there is an even more snazzy way but I believe it would be simple to implement and would please everyone.
Some days I would just like to get my one win of the day but I'm not always sure what time I had finished my game the day before so it ends up being a guess. Other than that I would like to say good job to Riot. You guys make a great game and it is entirely free. I support you guys 100%. Please post any feedback you guys have or any other ideas. I would really like to see this idea go through.