Recent RCT in timing of administration of tpn on day 1 and day 8 was in favour of day 8 in picu but still timing in some cases with clinical assessments if nutritional status,energy requirements, physiological difference

For example

Post major operations in GIT short bowel operations we usually start central TPN from day 3 or 4

For short period NPO patients we usually use partial nutrition in peripheral line

Ref:

Jimenez L, Mehta NM, Duggan CP. Timing of the initiation of parenteral nutrition in critically ill children. Curr Opin Clin Nutr Metab Care. 2017 May;20(3):227-231. doi: 10.1097/MCO.0000000000000369. PMID: 28376054; PMCID: PMC5844227.