The Morning Of: Cook the corn for the salad, which can be kept in the refrigerator up until you're ready to serve it.
A Few Hours Before: Make the granita and put it in the freezer, stirring the mixture every 30 minutes to scrape the edges and break up any ice chunks as the mixture freezes (this will take about 3 hours). Boil the potatoes for the smashed potatoes. Chop the vegetables for the chicken.
An Hour Before: Put the chicken and potatoes in the oven. Start the soup broth, sautéeing the mushrooms the stock reduces.
When Ready to Eat: Toss the cucumber and corn with the dressing, and let sit while you start the meal with soup. Then, bring all the dishes to the table.
After The Party: Have leftovers? The corn and cucumber salad is delicious over basmati rice for lunch the next day. The chicken can be piled onto sandwiches, thrown over a salad, or made into chicken salad.