When playing mini-metro at what passenger numbers do you get bonus items? I am trying to figure out how I can plan ahead and ect and this information could be extremely useful.
To summarize some of the other answers and comments:
Normal: You receive the bonus at the end of each In-Game Week
(after Sunday night is over, as shown on the clock in the upper-right corner)
Endless: You receive the bonus when you reach an Efficiency Milestone
(maintaining a certain number of passengers transported in a single day)
Extreme: (the bonus is the same as Normal mode)
A more complete explanation of each mode has already been written up in this excellent Q&A:
What are the differences between the game modes?