One of the most stressful times for a teacher is right around report cards. Save yourself from a LOT of stress, and start a routine to keep up with your marking and inputting.
Start now. It is never too early. It will get to be too late. And who among us really enjoys spending all of their "spare time" the week before report cards on nothing but report cards? Wouldn't it be nice, when report card time rolls around, if you could still have a social life?
Find a schedule that works for you, but at the minimum, you should be entering your marks into either the report card software or another compatible software every two weeks. Preferably every week. Entering marks in 10 or 15 minute chunks, every week will save you hours in front of that screen with a deadline and a lot of stress.
It all comes back to the old adage: 'How do you eat an elephant? One bite at a time.'
It may be easy to put off entering your marks for another couple of weeks, but that turns into a month or two, or even three very quickly. Remind yourself that you want to relax during report card season. Try it once. You'll never switch back.