Preallocated?

Any of them might be redundant. Context, please. It's hard to decide without some.

Cookbooks say "preheat the oven." Why not just "heat the oven"?

"The first turn is allocated to the host." There's no reason for "pre-." The context makes clear that the arrangement is made in advance.

"Prespecified" will be understood whether or not anyone has used it before, but the other consideration is whether you need to use it. Does "pre-" add any meaning?

I agree with reph's comments.

However, it sounds as though you are writing either a "how to" manual, or a technical article giving the inside scoop to how talk shows work. If that's the case, and the targeted publication habitually uses such terms (and expects to see them), then use the terms that are expected. This, of course, means you'll have to research other books or articles that deal with a similar subject.

If your work is indeed a manual or technical article, but your target audience is the laypeople, the terms you've listed do sound pretentious. One or two may not be a problem, but too many will lose your audience's interest. Tone them down a bit by questioning whether or not "pre" is really needed. Even though one or two cases might require it, see if there's an alternative. Try an online thesaurus (Google for one--there must be a dozen decent ones out there).

Warren