If you may, could you show a picture of your tree, then maybe we can give you a better guess. If you can give an estimate, on what it's in, you know, bare roots packed in peat moss, or something to keep them moist, or packed in a neat little pot, that will keep it for months.
But then, elms can take a lot. If you grown and transplanted bunches of plants all your life, don't worry. If you've never had a plant, then study and, dive in, join us.