How long after drinking alcohol should I wait before having CBC/platlet blood test? Can having a few drinks 3 nights before blood test skew results??

No alcohol. Alcohol is a poison that never did anybody any good, ever, so stay away from it. It may or may not affect your lab results, but I can say for certain that it will not do you any good.
Wish you good health! - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form.
Practice safe sex, if you have sex.
Go ahead and drink. It's best to get these labs done while you're in your usual lifestyle and state of health. If you're actually hurting your liver with the alcohol, it'll show as elevated transaminases and it'll be a warning to you. I'm fine with your drinking safely if that's what you do. Best wishes.