Michael, to refute Stahlecker's words, you have to show that Lithuanians instigated the pogroms before ANY German advance guard arrived in the region. The burden of proof thus lies with you to supply a date when the advance guard arrived. Stahlecker clearly states (see above) that it arrived before the actions started. You have to refute that.
The crucial issue is not the date on which the very first German soldiers arrived in Kaunas, but whether Lithuanian nationalists, particularly the members of the Lithuanian Activist Front, acted independently and without German instigation in the period between 21 and 28 June 1941, in attacking and imprisoning or killing persons whom those nationalists claimed were collaborators with the Soviet regime that had just collapsed.
In my posts, I have relied on the essay "Nazi Policy toward the Jews in the Reichskommissariat Ostland, June-September 1941: From White Terror to Holocaust in Lithuania", by Michael McQueen, in the book "Bitter Legacy : confronting the Holocaust in the USSR" (edited by Zvi Gitelman: Bloomington : Indiana University Press, c1997).
McQueen concludes that the killings carried out by Lithuanian nationalists before June 28 were independent actions. He states that by 28 June, the German authorities had put an end to those independent actions and dissolved the Lithuanian nationalist organisations such as the LAF. Thereafter, some of the nationalists were recruited into ppolice units by the German occupiers, who used them to institute a "White Terror", beginning on 4 July.
Readers may wish to disagree with McQueen's thesis, but I suggest they read his essay first.