What is the earliest example of Aryanization in Germany?

The date 1932 is correct in this case, but not as an example of the later quasi-official policy of 'aryanisation'.

Goldsmith could also see that the influence of the Nazis was considerable even before the actual assumption of power from the fact that his father was forced in the autumn of 1932 to sell the house and property in Gartenstraße to a party member and minister far below its value. In March 1934, he himself was asked to leave the conservatory in Sondershausen in order to make room for an "Aryan" student.

_{— Peter Petersen: George Goldsmith, in: Lexikon verfolgter Musiker und Musikerinnen der NS-Zeit, Claudia Maurer Zenck, Peter Petersen, Sophie Fetthauer (Hg.), Hamburg: Universität Hamburg, 2018 (https://www.lexm.uni-hamburg.de/object/lexm_lexmperson_00007228).}

It is well attested, but a symbol of the already present local terror power the nazis exerted. In Oldenburg the NSDAP had 37,2, 48,4 and 46,5% of the votes in 1931–1932. 'Aryanisation' was on the agenda for them since the 1920s. (This very case brought a slew of slightly embarrasing, even smallishly scandalous errors during commemorative actions. Wrong address, even wrong name…)

The local newspaper, the plaque:
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Actions like these were indeed quite in line with policy from 1933–1938, in which 'aryanisation' was 'voluntary', just like the above.

Some writers consider that the first kind of “aryanization,” which came to be a major feature of the early years of the dictatorship, was in fact already under way well before Adolf Hitler became chancellor of Germany on January 30, 1933. Avraham Barkai wrote: “The anti-Semitic boycott had already begun several years prior to the Nazi seizure of power and was intensified particularly during the 1929–1932 Depression. Both the appeal and the impact of this boycott were enhanced by the fact that Jewish economic activity was concentrated in a small number of especially prominent or crisis-prone branches of the economy.” Such areas included banking, which came under regular attack from the party for being intrinsically speculative and “Jewish,” but also department stores (which had the same reputation), the garment and shoe trade, and cattle dealing. Some Jewish business fields were vulnerable on purely economic grounds. Probably the most extreme example of a “pre-Nazi crisis” is the Leipzig fur trade, which collapsed during the world depression (see Chapter 5.)
_{— Harold James: "The Deutsche Bank and the Nazi Economic War Against the Jews. The Expropriation of Jewish-Owned Property", p35–36, Cambridge University Press: Cambridge, New York, 2001.}

The first 'aryanised' company in the Saar was the Walsheim brewery. Even before the Germans in the Saar region voted with 90,73 for Hitler in an internationally recognised as free election, the Jewish owner was forced out in 1935.(PDF)

What is called 'Aryanistion' in common historical research started indeed only on 1. April 1933, formalised with the first specific law Law for the Restoration of the Professional Civil Service on 7 April 33, which contained an "Aryan paragraph".

While from April 1933 on these occurred sporadically, 'just drive out the Jews, withot their property, preferably; by local initiative form party officials, or local competitors, and other private, non-state actors, this development took up speed much after 9 November 1938.

At least until 1987 most such entities with switched ownership 'celebrated' these occasions as the 'foundational date of the company'. Recently, this was a little frowned upon…

Which house, company or other property is counted 'officially' as the first case of post 1933 'aryanisation', not by pure force but with may be a matter of definitions or opinion.

For example, the wide spread boycott of retailers – destroying the livelihood of their owners – started before but already in February 33 had some 'successes'. Small businesses, department stores and manufacturing had many 'aryanisation' techniques applied, not always as an early complete takeover.

The Pankow based Engelhardt-Brauerei was denounced as "Jew Beer" immediately, came predictably into financial troubles, but was fully 'aeyanised' only in 1934. Radio electronics Loewe had immediate trouble in 1933, founders and family members fleeing, board of directors 'complemented with Aryans' by April, yet English Wikipedia counts this as completed only for 1938… (But compare this misleading portrayal for that and the brewery with Christof Biggeleben (Ed): "Arisierung in Berlin 1933 bis 1945", Berlin: Netzwerk Unternehmensgeschichte. Berliner Forum für Unternehmensgeschichte, Metropol, 2007. (gBooks))

_{— Wolfgang Dreßen: "»Aktion 3« Deutsche verwerten jüdische Nachbarn. Dokumente zur Arisierung ausgewählt und kommentiert", Aufbau Verlag: Berlin, 1998.
— Götz Aly: "Hitler's Beneficiaries: Plunder, Racial War, and the Nazi Welfare State", Metropolitan Books, 2007.}