No, you may not have merits discovery yet.

In a forceful statement against merits discovery before the resolution of a special appearance, the Fifth Court granted a writ of mandamus to require that “relator’s deposition be limited to matters directly relevant to the issue of jurisdiction if the deposition is taken before the trial court rules on relator’s special appearance,” because “Rule 120a requires discovery be limited to matters relevant to jurisdiciton prior to a ruling on a special appearance.” In re: Stanton, No. 05-17-00834-CV (Aug. 24, 2017) (mem. op.) (citing, inter alia, In re: Doe, 444 S.W.3d 603, 608 (Tex. 2014)).