In her recent book Die Familie Wagner Frau Hamann writes (among other things) on page 100:
Vom bevorstehenden Putsch in München, der Hitler die ›Machtergreifung‹ bringen soll, muss bereits in Wahnfried die Rede gewesen sein. Denn Siegfried bereitet für den 10. November ein Münchner Festkonzert im Odeon nahe der Feldherrnhalle vor, getarnt als Veranstaltung des ›Richard Wagner Verbandes deutscher Frauen‹.
This is more or less a repeat of the claim that Frau Hamann makes in the German edition of her Winifred biography. It seems to me extraordinarily unlikely that Hitler would have spoken of his putsch plans (in any case not finalised at that time) when he visited Wahnfried on October 1st 1923. At any rate it is plain that he did NOT mention the putsch to Chamberlain the previous evening, otherwise the latter would not have written his letter shortly afterwards praising Hitler as a ‚man of peace‘.
But Frau Hamanns suggestion seems to be that Siegfried specially arranged his concert in Munich to celebrate the putsch he knew to be coming. Again this seems to me highly unlikely (and the idea that he specially composed GLÜCK! for Hitler still more so). But what I have been seeking is evidence that the Munich concert was arranged before October 1st – i. e. when Siegfried first met Hitler. Clearly if the concert had been booked for the Odeon before October 1st, then it can have had nothing to do with Hitler and the putsch.