Assurance of already being justified is posterior to justification; justifying faith’s act is prior
Persuasion that one is already justified comes after justification itself.
The act of justifying faith comes naturally first, since faith is the means of justification.
Latin
XXIII. Praeterea modo descripta fiducia est aliquid posterius justificatione, & quod justificationem jam factam consequitur. Prius enim necesse est aliquem justificatum esse, quam ut vere sibi persuadere queat se jam esse justificatum. Sed fidei justificantis actus proprius atque specificus est aliquid, natura saltem, justificatione prius. Quandoquidem juxta Scripturae doctrinam, & Theologorum communem sententiam, fides est nostrae justificationis conditio, sive instrumentum.