This paper examines the rare but well-attested combinations of the Present Perfect with definite temporal adverbials denoting past time in US-American English. The goal of this paper is twofold. For one thing, it outlines the disemous analysis FDG proposes for the form have + past participle in its prototypical use, arguing that two different operators can reliably trigger this form, one marking anteriority and one encoding phasal resultativeness. For another, it shows how, via synchronic inferential mechanisms, the Present Perfect may have absorbed discourse pragmatic functions that now permit the felicitous use of definite temporal adverbials together with the Present Perfect in certain contexts. It is argued that this combination has routinized, taking over certain functions typically associated with the Present Perfect in a manner that suggests this development as potentially part of a grammaticalization process. The paper proposes that they are not as such part of the function the Present Perfect encodes, but that they currently represent a switch stage in the development of the US-American Present Perfect. It further suggests that in this switch stage, the combination of the Present Perfect with an adverb specifying past reference can be read as signaling the relationship between two Discourse Acts as justificational or can encompass the temporal specification as a necessary part of the action that is then available for a Resultative reading.