If you are doing keto diet for the first time it may take up to 3 days to deplete both liver and muscular glycogen and be fully into ketosis. This gets shorter the longer you are on a keto diet. For example I've been doing keto for 8 weeks now and after a carb load, I can achieve ketosis in less than a day.
To carb load sufficiently you should take in between 500g-1000g of carbs over the course of 1 or 2 days. I prefer to keep my carbups to less than 24 hours and I can easily eat about 500g of carbs in that time. Remember once your liver and muscles are filled with glycogen, any spillover gets converted to fat.