Heidegger and truth: a clue

Here is a great passage from Being and Time on truth that I will use as a clue to Heidegger's view on truth, which I will make explicit later sometime (in a clearer fashion than the sketch below):

In anticipation Dasein can first make certain of its ownmost Being in its totality--a totality which is not to be outstripped. Therefore the evidential character whcih belongs to the immediate givenness of Experiences, of the "I," or of consciousness, must necessarily lag behind the certainty which anticipation includes. Yet this is not because the way in which these [i.e. certainties, evidences] are grasped would not be a rigorous one, but because in principle such a way of grasping them cannot hold for true (disclosed) something which at bottom it [i.e. the way of experience, of the "I," of consciousness, etc.] insists upon "having there" as true: namely, Dasein itself, which I myself am, and which, as a potentiality-for-Being, I can be authentically only by anticipation.
-Being and Time, ¶ 54, 310.

For now, notice the difference between presence (holding for true, disclosing, which is not in the present but in the future through anticipation) and the present ("having there" as true). Because Dasein thrusts itself forward into the future, any attempt to access itself must also thrust itself in front of this thrusting, must anticipate it. In other words, Dasein must anticipate itself, or else it lags behind itself, since it is a potentiality-for-Being (i.e. a future-directed, possibility-oriented being). Furthermore, any truth it accesses about itself or its world will lag behind its authentic truth. A truth might be present to Dasein now, but because Dasein is forward-oriented, it lacks the ability to be a genuine presence for it. In other words, I might have access to a truth, but because I have not accessed this truth through anticipation of myself and my possibilities, it is already something that does not apply. As soon as it is there for me--i.e. present--it loses precisely its "there-ness," its ability to be grasped as applicable to my existence, its presence. This is why Heidegger goes on to say that "the ownmost possibility... is indefinite as regards its certainty:" whatever is a presence that is not present must be indefinitely grasped (for it is not present).
It should be clear that it is only because truth is determined not by what exists but by existence in accordance with the essence of time as the movement of presencing without present that all this is the case--this is why time is so important for Heidegger, why he consistently calls it the "horizon of Being."