When given a deadline many people take that to mean this is when they should TRY to get the project done.
First of all, deadlines should be looked at as the last possible time a project should be finished. Rather than planning on finishing by the deadline, plan on finishing as soon as possible. Then, if things take a bit longer than expected, you will still be within the time allotted
For some, the best method is to create an artificial deadline. If something is due on the 30th, set an official deadline on the 15th. Work toward that deadline as opposed to the one later on.
Whichever way you choose to handle your deadlines, take them seriously, plan on finishing ahead of schedule and look at the deadline as a worst case scenario instead of a hoped for scenario
Have a great day!