A 45-year-old man is admitted to ICU with severe acute pancreatitis (Atlanta classification: necrotising pancreatitis with organ failure). He is intubated and ventilated, on noradrenaline 0.1 mcg/kg/min. On day 2, the dietitian asks about nutrition. According to ESPEN/ESICM guidelines, what is the recommended route and timing of nutritional support?