This is basically the "Bill-and-Ted theory" of time travel you're asking about. Is it possible to go back in time and set things up in the past that you will require in the present or future?
Let's think of a simpler example. Hermione is rushing to class. She plans to take class A, and then spin back time so she can attend class B at the same time. However, she realized on the way that she's forgotten the book for class A. Could she plan to wait until after class A, and then spin back time, go back to the Common Room, grab class A's book, leave it for herself outside the classroom, and then hurry to class B? And having made that plan in her mind, could she then reach behind the plant outside class A and instantly find her book waiting for her? (What's really interesting to ponder, though, is if she already has the book at the end of class A, does she really need to go all the way back to the Common Room to get it before she stashes it? And if she doesn't, how did it get there in the first place?)
The answer would seem to be yes, these kinds of temporal causality loops are possible. After all, if Harry hadn't cast the Patronus charm to save himself, he wouldn't have survived the Dementors in order to go back in time and cast the charm to save himself. True, that wasn't so much a plan in the way of intentionally planting something he would need, but he does state afterward that the only reason he could cast the Patronus was that he had the knowledge that he'd already done it, which is a clear example of the future influencing the past.
In that sense, the Time Turner doesn't prevent paradoxes, because a temporal causality loop is a paradox. They only survived because they were able to save themselves, thus ensuring they could go back in time and ensure they survived.
Given that example, I find it completely plausible that one could be in a confrontation with a Death Eater and, say, after having been disarmed, think to oneself, 'After I get out of this, I'll get a second wand and come back here and hide it behind this rock.' And, with that in mind, the wand will already be in place, allowing you to neutralize the Death Eater, and then turn back time and leave the wand you already have back under the rock for you to find. It's a complete paradox, because where did the wand come from, but it's a completely self-contained paradox, and the Time Turner does seem to allow for those without any difficulty.