And I know this will sound super Dumb, but DRINK MORE WATER.
If You are doing this for Your health, (because being honest that's the number one reason to go Vegan), You probably overeat; The sensation You will get eating only fruit and veggies after You switch diets is similar as Drinking lots of Water.
You will feel bloated and hungry, since You are not used to, (Most of People have a very low intake of Water, Fruits and Veggies) You are used to feel "Stuffed" . So at least 2 weeks prior going to get all Your Vegan Groceries, DRINK MORE WATER.
If You need a Donut, *Drink a glass of water* ; You need one more Plate of that Yummy Soup, *Drink a Glass of Water* instead. How many of Us used to serve double load of Spaghetthi because "WHY NOT?" and felt super Stuffed and Sleepy afterwards.
If You are able to handle 2 weeks subbing -Flours, Sugars,Coffee,Soda- for water then You are good to go.