I have found that in my testing the field's change event is not triggered until the upload is complete only when previewing a form.  Once the form is used by starting the actual process it does wait for the upload to complete before triggering.  My upload field is in a collection.  

$('.cf-collection').on("change", ".upload", function(event) {
	var collectionRow = $(this).closest('.rpx');
	var imgPreview = collectionRow.find('img.previewImage');
	console.log(imgPreview);
	imgPreview[0].onload = function() {
		Test(collectionRow);
	}
});