Get a giant laminated wall chart and put on all of your assignment deadlines and other important commitments.
Work back from each for a date by which you MUST start working on, or preparing for, each item. I would suggest a minumum of 2 weeks lead time.
That way you know if you pass that date, you are storing trouble for yourself.
Look out for hot spots where, eg more than one thing is due on the same date and extend the lead time.
Take into account the weightings of assignments. Work to pass everything obvs but allocate more time to assignments weighted at 70%+.