Here is the code from the Advanced Editor for those who prefer not to download the file (red text refers to paramters but can be replaced with hard coded dates or dynamic retrieval of earliest and latest dates in you Fact table).
let
DayCount = Duration.Days(Duration.From(EndDate - StartDate)),
Source = List.Dates(StartDate,DayCount,#duration(1,0,0,0)),
TableFromList = Table.FromList(Source, Splitter.SplitByNothing()),
ChangedType = Table.TransformColumnTypes(TableFromList,{{"Column1", type date}}),
RenamedColumns = Table.RenameColumns(ChangedType,{{"Column1", "Date"}}),
InsertDayName = Table.AddColumn(RenamedColumns, "DayOfWeekName", each Date.ToText([Date], "dddd"), type text),
InsertDayWeek = Table.AddColumn(InsertDayName, "DayInWeek", each Date.DayOfWeek([Date],6)+1),
InsertWeekEnding = Table.AddColumn(InsertDayWeek, "WeekEndingFriday", each Date.EndOfWeek([Date],6), type date),
InsertCurrentSaturday = Table.AddColumn(InsertWeekEnding, "CurrentSaturday", each Date.AddDays([Date], -Date.DayOfWeek([Date],6)), type date),
DateOffset = Table.AddColumn(InsertCurrentSaturday, "Offset", each Date.FromText(Number.ToText(Date.Year([CurrentSaturday])) & "-02-01") - [CurrentSaturday]),
#"Changed Type" = Table.TransformColumnTypes(DateOffset,{{"Offset", Int64.Type}}),
InsertISOWeekFeb1 = Table.AddColumn(#"Changed Type", "ISOWeekFeb1", each if [Offset] > 6 then Date.FromText(Number.ToText(Date.Year([CurrentSaturday])-1) & "-02-01") else Date.FromText(Number.ToText(Date.Year([CurrentSaturday])) & "-02-01"),type date),
InsertISOWeekYear = Table.AddColumn(InsertISOWeekFeb1, "ISOWeekYear", each Date.Year([ISOWeekFeb1])),
InsertISOWeekFirstSat = Table.AddColumn(InsertISOWeekYear, "ISOWeekFirstSat", each if [CurrentSaturday] < [ISOWeekFeb1]
then Date.AddDays([CurrentSaturday],0)
else Date.AddDays([ISOWeekFeb1], - Date.DayOfWeek([ISOWeekFeb1],6) ), type date),
InsertFYWeekNum = Table.AddColumn(InsertISOWeekFirstSat, "ISOWeekNum", each Number.RoundUp(((Duration.Days(Duration.From([Date] - [ISOWeekFirstSat]))+1) /7 )), type number),
FiscalYear = Table.AddColumn(InsertFYWeekNum, "FY", each [ISOWeekYear]+1),
InsertFYWeekID = Table.AddColumn(FiscalYear, "ISOWeekID", each [FY] * 100 + [ISOWeekNum], type number),
InsertIFYWeekNameLong = Table.AddColumn(InsertFYWeekID, "ISOWeekNameLong", each Text.From([FY]) & "-W" & Text.End( "0" & Text.From([ISOWeekNum]),2) & "-" & Date.ToText([Date],"ddd")),
#"Renamed Columns" = Table.RenameColumns(InsertIFYWeekNameLong,{{"ISOWeekNameLong", "FYWeekNameLong"}, {"ISOWeekID", "FYWeekID"}, {"ISOWeekNum", "FYWeekNum"}, {"ISOWeekFirstSat", "FYWeekFirstSat"}}),
#"FY Quarter" = Table.AddColumn(#"Renamed Columns", "FY Quarter", each if [FYWeekNum] <= 13 then 1 else if [FYWeekNum] >= 14 and [FYWeekNum] <= 26 then 2 else if [FYWeekNum] >= 27 and [FYWeekNum] <= 39 then 3 else 4),
#"Week of FY Quarter" = Table.AddColumn(#"FY Quarter", "Week of Quarter", each if [FYWeekNum] <> 53 then ([FYWeekNum] - (Number.RoundUp([FYWeekNum]/13)-1) * 13) else 14),
#"Quarter Week ID" = Table.AddColumn(#"Week of FY Quarter", "QtrWeekID", each [FY Quarter]*100+[Week of Quarter]),
#"FY Quarter ID" = Table.AddColumn(#"Quarter Week ID", "FYQtrID", each [FY]*100+[FY Quarter]),
#"Changed Type1" = Table.TransformColumnTypes(#"FY Quarter ID",{{"FY Quarter", Int64.Type}, {"Week of Quarter", Int64.Type}, {"QtrWeekID", Int64.Type}, {"FYQtrID", Int64.Type}}),
fnPeriod454a = (weekNum) => let
Periods =
{
{(x)=>x<5, [P=1, M="Feb"]},
{(x)=>x<10, [P=2, M="Mar"]},
{(x)=>x<14, [P=3, M="Apr"]},
{(x)=>x<18, [P=4, M="May"]},
{(x)=>x<23, [P=5, M="Jun"]},
{(x)=>x<27, [P=6, M="Jul"]},
{(x)=>x<31, [P=7, M="Aug"]},
{(x)=>x<36, [P=8, M="Sep"]},
{(x)=>x<40, [P=9, M="Oct"]},
{(x)=>x<44, [P=10, M="Nov"]},
{(x)=>x<49, [P=11, M="Dec"]},
{(x)=>true, [P=12, M="Jan"]}
},
Result = List.First(List.Select(Periods, each _{0}(weekNum))){1}
in
Result,
InsertPeriod454 = Table.AddColumn(#"Changed Type1", "Period454Record", each fnPeriod454a([FYWeekNum])),
#"Expanded Period454Record" = Table.ExpandRecordColumn(InsertPeriod454, "Period454Record", {"M", "P"}, {"M", "P"}),
#"Renamed Columns1" = Table.RenameColumns(#"Expanded Period454Record",{{"M", "FY Month Name"}, {"P", "FY Month ID"}}),
#"Removed Columns" = Table.RemoveColumns(#"Renamed Columns1",{"CurrentSaturday", "Offset", "ISOWeekFeb1", "ISOWeekYear", "FYWeekFirstSat"})
in
#"Removed Columns"
