One has to work on the report and perfect it before submission. So find ways to quickly produce quality reports first and submission on time is almost automatic. for that simply select the right person for the job and motivate him/her throughout the process; Make sure you are part of it.
Before asking a report on any item of Math be sure of teaching the weakest student to understand the particular math item. Also before hand declare the value of on time submission of report and loss of failing to do so on time.