Based on the information given the following would be the norm. It still amazes me how many mistakes I see with this. I am assuming that we are talking only about the Triodian Period.
Which day's saints does your priest commemorate at the following services:
A. Compline, Monday, 7:00 p.m., Monday or Tuesday?
First off it should be Great Compline that is celebrated. There is no daily saints commemorated during this service. This service is after Vespers so it is part of the Tuesday cycle.
B. Presanctified Liturgy, Wednesday, 5:00 p.m., Wednesday or Thursday?
Presanctified Liturgy is Lenten Daily Vespers with communion so it starts the Thursday cycle. If 9th Hour is celebrated before hand then it would close the Wednesday commemoration.
C. Salutations to the Theotokos, Friday, 7:00 p.m., Friday or Saturday?
This service is Small Compline and is part of the Saturday cycle. This is not a Lenten service since it is part of the Saturday cycle. This is why the troparian of St. Theodore is sung at the firsts one since he is the major commemoration of the 1st Saturday of Lent.