Daily reward

When I take my daily reward (for example 1 favor), it takes 20 hours before I can take the next one (2 favors). But how much time do I have to take the 2 favors, before they are reset to 1? I sometimes habe the feeling that I'm too late and have to start again with 1.
It would be nice to have 24 hours time to collect. Eather 24 hours after the 20 hours are over or just every day once between 0 o' clock and 24 o' clock.