There are 4 sim periods for the CU upgrade.
Days 1 & 2 are usual LPC failures, approaches from the left seat, nothing unfamiliar. These can be instructed by an SFI FO.
Day 3 is a LOFT usually conducted by a TRI/TRE, Day 4 is a LPC conducted by a TRE. Obviously an FO SFI can't do day 3 & 4.