Within the framework of historical sociolinguistics, the present study deals with the incidence of the textual axis at the dawn of a change affecting relative obliques in early modern Spanish. To this end, both the diffusion and the conditioning of the new variant (en + art + que), as opposed to the traditional one (en + que), are studied comparatively in two corpora composed of texts close to immediacy (private correspondence) and communicative distance (literary and legal-administrative) from the eighteenth century. The results of the study show, on the one hand, that the expansion of innovative forms was significantly greater in the documents of immediacy than in those of distance. On the other hand, it is found that, despite largely similar internal conditions, some of them exhibit idiosyncratic behaviour revealing a certain disparity in these initial stages of change. All this highlights the need to include textual typology in the study of language variation and change, alongside the usual linguistic and extra-linguistic factors. Keywords: historical sociolinguistics, linguistic variation and change, discursive traditions, prepositional relative clauses, early modern Spanish