1. TuG A breaks enemy TuG B in Fighting Phase
2. TuG A follows up into enemy TuG C at end of Fighting phase.

Q: when can TuG A step forward?

Q: when can TuG C align with TuG A 

Press forward (not step forward) occurs once contact has been made (9.4 F.3 p78).

Alignment can occur at points 2.7, 4.1 and 5.1 in the turn sequence.  This is after all charge moves have been completed, at the start of the movement phase or at the start of the fighting phase. (QRS).