Tempore is in ablative case, and in english there isn't a good substitute. This means it isn't a static set time event, it has some leeway so to speak. German has the ablative case, so I think it works out for them.
The Latin prepositions cum (with) and sine (without) are always followed by the ablative case. German has grammatical cases too, but no ablative. The German propositions mit (with) and ohne (without) are followed by the accusative case.
So c.t. = cum tempore = mit Zeit = with time (or with some delay), and s.t. = sine tempore = ohne Zeit = without time (or without delay).
That doesn't change anything else you said, though :)
And of course, as everyone has already mentioned, spookie's comment is complete nonsense because the case is required, and fully explained, by the prepositions.
> German does not have ablative case