Cutting a legitimate 10# when you are already 8-10% bodyfat is kinda rough. You can easily shed some water, comfortably getting around 5# off. Another 5# of water cutting kinda sucks to cut, so it's up to you if you wanna cut water or actual fat. If you are weighing in the day of the competition, i wouldn't cut more than 5# of water. If you are weighing in right before you step on the mat (like at IBJJF tournaments), I wouldn't cut any water.
If you really wanna drop your carbs to lose weight, that's your call, but it's not pleasant trying to do multiple fights with depleted glycogen.
If you are competing at like a brown/black level, then dropping the weight may be important. If you are competing at a white/blue/purple level and you are 8-10% bodyfat, i would just relax and focus on skill and just fight at your weight. the only time I ever felt like i got beat by somebody and weight was an issue was during absolutes when the guys outweighed me by 40-60#. if you are that lean at 158#, you should be fine.