I didn't. I lost 1 pound the day after and went down from there. I will suggest easing off protein right before you switch the diet though, and moderate carbs and protein in the first couple of days of switching
It depends how many carbs you eat in the first couple of weeks. If you have been following a low carb diet your glycogen stores will be depleted.That's why you initally lose a lot of weight in the first week on a VLCD or low carb diet. Once you start to introduce carbs your liver will store a mixture of glycogen and water. Any weight you "gain" (as long as you're in negative energy balance) will only be water weight and not fat.