cum with the indicative means "when"; with the subjunctive it means "when", "since" or "although, whereas", and only the sense decides which.
First make sure it is not the preposition: cum + an ablative noun, with no verb of its own, is "with" (cum dolore, cum voluptate).
cum + indicative: "when, whenever", a plain statement of time: cum voluptati vel dolori succumbit "when it gives in to pleasure or pain".
cum + subjunctive: "when" (in past narrative, with the imperfect or pluperfect), "since" (cum nec honesta ea, nec inhonesta sint "since they are neither honourable nor shameful"), or "although, whereas". A tamen in the main clause points to "although".
cum … tum is a pair, "both … and especially" (see paired words).