Putting a date on the calendar gives you a target to shoot for.
If you are a procrastinator like me then if something isn’t due then it will not get done. This is due to Parkinson’s Law which states that work expands so as to fill the time available for its completion. People usually take all the time that they are given.
To solve this figure out what needs to be done, estimate how long it is going to take and set a deadline that you can attain.