Instant Upgrades can be done to speed up building and/or upgrades. If an IU is attempted with five minutes or less time remaining, the IU will cost minerals. If more than 5min remains, it will cost galaxy chips. By knowing more about this, we can determine if it is a good idea to wait a few minutes--to save valuable chips.
(h)our, (m)inute, (s)econd
0h 00m 01s - 0h 05m 00s = (minutes_left * 50) minerals
0h 05m 01s - 0h 43m 00s = 1 chip
0h 43m 01s - 1h 13m 00s = 2 chips
1h 13m 01s - ?h ??m ??s = 3 chips
Feel free to help figure out where the times begin and end. Seems like the brackets last for 30-40min and I do know that 1h 44min is in the 4chip bracket.