Let me see if I understand what you are asking:

You have a form which is filtered based on a query. That form has a subform that is also filtered based on another query.

Are you asking how to make the subform not filtered when it initially loads, or how to not even load the subform until some action is taken in the main form?

Yes

If you're wanting it to load all records until you enter the year, then just have the query that the subform is based upon show all the records (remove the filter from the query), then in the After Update event of the year field, set the filter of the subform's form and turn the filter on. This would be done w/ VBA:

Details

Private Sub YEARFIELD_AfterUpdate()

     DIM S as String

     If Not IsNull(YEARFIELD) Then
          S = "Year=" & YEARFIELD
     Else
          S = ""
     End If

     SUBFORM.Form.Filter = S
     SUBFORM.Form.FitlerOn = Not IsNull(YEARFIELD)

End Sub
Copy

Replace YEARFIELD with the name of the field you are getting the Year from. Replace SUBFORM with the name of your subform control. Replace "Year" in S with the field in the query you are looking at. If it's a date field, you'll need to adjust for that by wrapping YEARFIELD in hashtags (#) inside of quotes.

Alternatively, if you just don't want the subform to load at all until a year is entered, then I would make the Source Object of the sub form blank initially and set the subform's visibility to no. Then, again in the After Update event of the Year field, set the Source Object and make the subform visible, again w/ VBA:

Details

Private SUB YEARFIELD AfterUpdate()

     If IsNull(YEARFIELD) then
          SUBFORM.Form.SourceObject = ""
          SUBFORM.Visible = False
     Else
          SUBFORM.Form.SourceObject = "QUERYNAME"
          SUBFORM.Visible = True
     End If

End Sub
Copy

This assumes that the query gets its filter from the form. If not, you'll need to add the stuff from above.

The main issue is that if your subform is based on an already filtered query, you either have to change the filtering in that query on load or change the query itself. Here are some links that relate somewhat:

On Filter
Requery Subform

Richard has plenty of videos on Filtering, Subforms, and Queries, these are just a couple

Awesome! Thank you very much.