Former wrestler here. Don't do it over 3 days. Do it in as short as a time frame as possible
. So, ideally the morning of if there is enough time to get a good sweat in and then hydrate immediately after weight in. Salt is the only thing to massively restrict a few days out. Also, don't listen to all those guys saying easy to lose 8 lbs blah blah blah. They probably weight 180 lbs (like me) and as a percentage of body weight that can change the difficulty of cutting weight. So, cutting about 2% of body weight can have some impacts on performance. Ideal is short and sweet and replace right after weigh in.
Also a former college wrestler and former college wrestling coach and 100% this. The shorter the time you are dehydrated, the quicker and better your recovery. Also, knowing your sweat-rate helps. Some guys can lose 8+ pounds an hour, and others can only lose 2-3. Generally smaller people lose less.
We used to encourage our guys to eat enough the night before a weigh-in so that they would wake up anywhere between 1-4 pounds overweight (depending on what they could lose in 40-50 minutes). It also helps to know how much you generally float (lose) overnight. Then working out to cut that weight before weigh-ins basically functions as a good warm up for that days tournament.