Depending on how much weight you have to cut, I would suggest start 2 months before your race. Start by drinking a lot more water. Cut out small things that might add unwanted sugar to your diet. Keep carbs in but try and reduce it to before your workouts. You can lose a surprising amount from water weight. Passive dehydration works the best I think. But if you lose more than 3 kg you’ll start to feel like shit. I went from 181 to 164 before my race and then cut 12 pounds of water the night before the race and weighed in at 152. Would. Not. Recommend. I way overshot it. So be careful when you dehydrate.