I think you are right to acclimatise the tree slowly this season and moving it out when the worst of the frost has gone is a good idea. I have put a young 3 litre Wollemi on my patio, plunged in a pot and it looks quite happy still, even though air temperatures in my garden have gone down to -3 degrees. Addmitedly my garden is quite sheltered and the tree hasn't moved since it was put out in October. I am looking forward to seeing the new growth in the spring which I will probably protect if we have any late frosts.