davichi will most likely be back first just because it's been over a year since their last album, and t-ara's was only 6 months ago
i think it's safe to say they won't be making a comeback in may, the current speculations are saying it'll be sometime within the first half of june but who knows!!!!!
there's also the new girl group CCM is debuting. they were supposed to debut this month, but that was probably put on hold for a few months if Jiwon is really in it, as she recently suffered from a knee injury and had to get surgery for it.