What is a good schedule of weight gain if I am pregnant with twins?

Focus on diet. I don't set any specific weight targets for my patients. Focus on eating a healthy diet, rich in fruits and vegetables, lean protein, hearty complex unprocessed carbohydrates, etc. If you have access to food, then eat healthy. Expect that you will likely gain more weight with twins than with one, but i don't think you should focus on the pounds. Focus on your nutrition instead.
35 pounds average. Weight gain for a woman at ideal body weight is approximately 25 pounds with a single baby and 35 pounds with twins. Less if you are overweight.