I think that it's different for everyone. Typically, I don't have my clients load or deplete carbs. I DO, however, manipulate their carbs during the last week. Most of my clients are on a carb cycle, with lower days and higher days. During the last week, I might have them do two or three higher days in a row in the beginning of the week, then drop them down to their lower days for the couple days leading into the show. Carbs hold water subcutaneously, therefore, I try to keep their carbs lower around the time they have to step on stage. Since figure girls don't need to be super-compensated with glycogen, I find there isn't an immediate need to load the muscles with carbs. It's more important for a figure girl to be a little tight package than bulging with rounded muscle bellies. EVERYONE is different though, so what works for one, may not work for another.
As for sodium, I find that keeping sodium in the diet until the last couple days works best.
Hope this helps