You need to be really careful; the danger is that if you allow it to thaw at too high a temeprature, the outer portions will become suitably warm for the runaway reproduction of pathogenic bacteria before the inner portions are thawed - in the worst case, you could end up causing your guests to suffer food poisoning.
I’ve heard of people thawing it in a bathtub of cool water (water is a better heatsink than air, so it should thaw quicker even at an equally low temperature, but I’m not going to recommend this method because I don’t know enough about it (including whether it is at all safe).
I’ve thawed whole turkeys in cool water, but my concern is that you said yours is already cooked, so I’m not sure how well it will work.
First, I’d take it out of all wrappings, unless you are sure there is a completely sealed plastic cover to it. If you’re not sure, go find some kind of plastic bag (maybe an oven bag?) that it will fit into. Put the unwrapped turkey in the bag, put in the sink (or bathtub IF you think that’s clean enough). Run cold water in the the sink to cover the turkey. Replace the water every half hour - I’d say 2-3 hours and it should be thawed, but no guarantees.
Out of curiosity about my estimated times, I went to the butterball.com web site and found this (and that makes me think that I’m WAY understimating the time needed):