Google Analytics connector missing startdate/enddate parameters

Thank you for the above code. This works to circumvent the sampling issue!

I use a code like this:

let
    Source = GoogleAnalytics.Accounts(),
    #"1" = Source{[Id="999"]}[Data],
    #"2" = #"1"{[Id="999"]}[Data],
    #"3" = #"2"{[Id="999"]}[Data],
    #"Added Items" = Cube.Transform(#"3",
        {
            {Cube.AddAndExpandDimensionColumn, "ga:channelGrouping", {"ga:channelGrouping"}, {"Default Channel Grouping"}},
            {Cube.AddAndExpandDimensionColumn, "ga:customfield", {"ga:customfield"}, {"Customfield"}},
            {Cube.AddAndExpandDimensionColumn, "ga:yearMonth", {"ga:yearMonth"}, {"Month of Year"}},
            {Cube.AddMeasureColumn, "Revenue", "ga:transactionRevenue"},
            {Cube.AddMeasureColumn, "Transactions", "ga:transactions"}
        }),

 #"combinedData" = Table.Combine({
Table.SelectRows(#"Added Items", each ([Month of Year] = "201803")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201804")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201805")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201806")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201807")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201808")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201809")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201810")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201811")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201812")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201801")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201802")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201903")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201904")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201905")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201906")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201907")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201908")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201909")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201910")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201911")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201912")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201901")),
Table.SelectRows(#"Added Items", each ([Month of Year] = "201902")),
Table.SelectRows(#"Added Items", each Text.Contains([Month of Year], "2017"))
 })
in
    combinedData

This works, but for performance reasons and scalability I'm looking for an improvement over this as I now query again and again also the historical data. Ideally I would like to create a combined datasource that contains all data up till and including last month. And then have a seperate connection for the data for this month. And combine the two. That way I don't have to send all seperate monthly requests for the historic data anymore, which saves on GA requests. That historic datasource should of course update as soon as a new month starts, so for instance when August starts my historic dataset should automatically contain data up till and inclusing July 2018 (as I aim to avoid manual tasks).

Is this possible in the query editor? Anybody any ideas?