Assuming same day weigh in, don't use the above guide.
Weight cutting tips for same day weigh in:
Don't use laxative, mild or otherwise. Once the adrenaline hits you the after effects can be a bad combination. I'm sure I'm not the only one who's done a fight more concerned about shitting my pants than winning it.
Don't drastically cut carbs in order to lose the 4 pounds of glycogen weight and then refuel before the competition. Your body will rebound hard, with 24 hours time its enough to get over the sluggish/sick feeling of recarbing but if you try to do a complete carb load in less than 6 hours you are going to feel bloated, sluggish and most likely low on energy.
Don't cut more than 5 pounds in the last 24 hours. Being dehydrated will hurt your performance, I'm sure someone here has the statistic on the huge effect of even 1% dehydration on athletic performance. There is also a very real risk on brain/organ damage if you get dropped on your head.
Do tighten your diet over 2 months like suggested above to lower your body fat slowly. I've actually seen it suggested to use heavy weights and low reps to maintain muscle mass over the cut but i think at the end of the day you'd be hard pressed to notice a difference.
Do rehydrate with an aid like pedalyte to put back some of the crucial ingredients your body sweated out, and keep drinking until your pee turns clear.
Do eat some food 2-3 hours before you compete, and come prepared with food and drink for a long day.
[Professionals get around many of the above tips by having personal doctors ready to administer I.V.s right after the weigh in. It is a really common practice in Thailand from what i hear.]
Don't think I've ever cut weight for any tournament ever.
I was cutting from 77kg to 66kg for Muay Thai fights over 2 weeks with no effect on my fight performance.
For BJJ I won't bother, I've signed up for the next tournament in the 77-87kg class at 80kg.
I.V.s are also awesome when youre hungover. Banana bags take you from feeling like **** to ready to rock in 20 minutes