You excrete thx from your system by peeing, poo poo, ejaculate, crying and sweating.
Another thing I always Implement during such a time is I find a health club with a steam room. So do this. Go everyday between now and then and spend at least an hour a day sweating your ass off in steam room.
I usually go for hour day leading up to it. Like 10 minutes in, five minutes out 10 minutes in. You will sweat like crazy but it is moving metabolite out of your system and it is something you can do in addition to drinking fluids alone.
Sweating plus peeing will remove more than peeing alone.
Keep drinking fluids.
In addition, another benefit is after you leave the steam room for the day, you have boosted your metabolism for the day, so your body will be burning calories thru the day. Every drop of urine and sweat counts.