Fiscal Calendar Date Table

Please try out this approach that dynamically gets the start and end dates dynamically from your fact table. The first is the M/Power Query version (note this may cause performance problems as it will effectively load your fact table a second time to get these dates). The 2nd is the DAX version of same.

let
FactDates = List.Buffer(List.Distinct(FactQuery[DateColumn])),
StartDate = List.Min(FactDates),
EndDate = List.Max (FactDates),
DateList = List.Dates(StartDate, Number.From(EndDate - StartDate)+1, #duration(1,0,0,0)),
InitialTable = Table.FromColumns({DateList}, {"Date"}),
    #"Changed Type" = Table.TransformColumnTypes(InitialTable,{{"Date", type date}}),
    AddFY = Table.AddColumn(#"Changed Type", "FY", each Date.Year(Date.AddMonths([Date], 6))),
    AddFQ = Table.AddColumn(AddFY, "FQ", each Date.QuarterOfYear(Date.AddMonths([Date], 6))),
    AddFM = Table.AddColumn(AddFQ, "FM", each Date.Month(Date.AddMonths([Date], 6))),
    #"Added Custom" = Table.AddColumn(AddFM, "FW", each let 
FYstart = #date([FY]-1, 7, 1),
result = Number.RoundUp((Duration.TotalDays([Date] - FYstart)+1)/7, 0)
in 
result),
    #"Changed Type1" = Table.TransformColumnTypes(#"Added Custom",{{"FY", Int64.Type}, {"FQ", Int64.Type}, {"FM", Int64.Type}, {"FW", Int64.Type}})
in
    #"Changed Type1"

FiscalDates =
ADDCOLUMNS (
    CALENDAR ( MIN ( Sales[SaleDate] ), MAX ( Sales[SaleDate] ) ),
    "FY", YEAR ( EOMONTH ( [Date], 6 ) ),
    "FQ", QUARTER ( EOMONTH ( [Date], 6 ) ),
    "FM", MONTH ( EOMONTH ( [Date], 6 ) ),
    "FW",
        ROUNDUP (
            (
                INT ( [Date] - DATE ( YEAR ( EOMONTH ( [Date], 6 ) ) - 1, 7, 1 ) ) + 1
            ) / 7,
            0
        )
)

Pat