Night before.
Ended up with:2A* 4A 5B 1C
In retrospect, if I actually tried and put in more effort maybe I would have got better grades, but they're decent enough to get into most univerities as long as I get A*A*AA in A-Level.
I would spend more than just the night before as it's not exactly advisable, if you're aiming for those A*/A spend half an hour minimum on each subject every week, make sure you fully understand everything in each lesson, go and bug your teachers if you didn't, they're there to be bugged, especially if you want A-A*. Also, here are some general revision tips:
For every half hour of revision, give yourself a 5 minute break, getting a biscuit, a drink, texting a few friends, flicking through facebook, whatever you want, but only for 5m.
Don't spend longer than 4 of these sessions at once, i.e after 2 hours take a much longer break, a few hours maybe before starting again it really does keep you refreshed and allows you to reward yourself for the revision you've done. Also, don't stress about the exams, worrying about them won't get you grades; working will. Turn off any distractions when you're going to work. Then give yourself a day off/half a day off to do what you like, remember you need to still be happy :P. Also, GCSEs don't dictate your life as some people try to drill into you, but they defintely help, so go and get those A's and A*'s
Try as many past papers as you can before the exams, good luck!