What ester test is it again? Whenever you're on test your body is going to store more water in the muscle as well as hold more glycogen even with e2 in check you will still hold some more water and it gives your muscles that constant full look, so on test you will look fuller than someone who is natty when you guys are both are you most "depleted point". I think if you can come in lean enough while still on, holding a fuller look, then I would stay on for the show, but that's just me. I've heard of competitors taking doses of AI or nolva leading up to a show to dry out, but not sure on how effective it is. I don't know if crashing your e2 will rid your body of extra water compared to holding e2 in the normal range. I'd damn near just try going with a diuretic first. Though I do think coming off test will give you a "tighter" look, more crisp, so it's really a preference of what look you want to have on stage.
Edit: it also helps if you know exactly what the judges are looking for. Size wise, proportions, conditioning, see if you can't find a judge to befriend so for future shows you can get an inside scoop. I know one judge that helps me with posing practice which is cool cuz she can tell me exactly what they want to see