To target a specific day of the week (let's day this Wednesday), you can use the startOfWeek keyword in combination with an addition of a number of days.
The startOfWeek keyword designates the first day of the this week (depending on what you have in your settings for work week, Monday or Sunday). Adding two days to that will get you Wednesday
startOfWeek 2 +
startOfWeek 4 +
So the query to get all items scheduled for this Wednesday is:
startOfWeek 2 + scheduleDate ==
Similarly the query to get everything in a list that is due before Friday is:
startOfWeek 4 + dueDate <