I wouldnt cover until the very last moment or wait for sub dollar prices for sure if it goes there. Or wait for them to call you. If you have other equity in your account you might not have to cover for a little while even if this issue gets corrected soon.
But for sure I wouldnt cover until it shows minus(when the split gets officially corrected) or to the last waking minute. And this might drag out so it could be a long while to cover from my exp with ATNO.