FirstPage_LeftHand_1.0.jsx

//update version for FirstPage_LeftHand.jsx 
//refer to  https://indesignsecrets.com/starting-a-document-on-a-left-hand-page.php
if (app.documents.length !== 0) {
    app.doScript(function() {
        try {
            var d = app.activeDocument;
            d.documentPreferences.facingPages = true;

            // d.spreads.everyItem().allowPageShuffle = true;
            for (var i = 0; i < d.pages.length; i++) {
                d.pages[i].parent.allowPageShuffle = true;
            };

            p1 = d.pages[0];
            p1.appliedSection.continueNumbering = false;
            p1.appliedSection.pageNumberStart = 2;
            d.spreads.everyItem().allowPageShuffle = false;
            //d.spreads[0].allowPageShuffle = false;
            p1.appliedSection.pageNumberStart = 1;

        } catch (e) {}
    }, ScriptLanguage.JAVASCRIPT, undefined, UndoModes.ENTIRE_SCRIPT, "FirstPage_LeftHand");
}