You can poach the shrimp up to 48 hours in advance and store covered in the refrigerator. Next, slice, julienne or grate your green mango up to 24 hours in advance and drizzle with a little lime juice and store covered in the refrigerator. If desired, you can make your prik nam pla sauce 24 hours in advance or the morning of your gathering. Just before your guest arrive, toss the shrimp, prepared green mango and prik nam pla sauce together. Add the crushed roasted peanuts upon serving.