tant de bo + Subjunctive

Tant de bo vingui demà expresses a wish about a possible future event. Imperfect subjunctive can express a more remote wish about the present or future: tant de bo tingués més temps. The expression does not assert that the wished-for situation is true.

For regret about an unrealized past event, use pluperfect subjunctive: tant de bo hagués vingut. Choose the time and degree of remoteness deliberately rather than treating all three tenses as interchangeable translations of I wish.

The wished-for clause can stand on its own after tant de bo. In ordinary writing no que is needed between the expression and the verb. An exclamation mark can convey emotion, but it is not required to make the construction grammatical.