Developer record

Can anyone explain how to know what the developer record is on any given level before playing it? Or do you just have to keep trying to get quicker and hope that eventually you'll beat it?

Developer records are the record for points, not just time. Yes, its just trial and error to try to balance the right time with resources. Obviously the best strategy is to try furiously to get the most resources in the shortest amount of time while still completing all the goals, including the bonus goals. The most elusive records are often missed because there is a well hidden chest that has not been opened, or the 2x bonus was not used when collecting coins/chests.