Hello, just to give you some information. Right now the process is seamless, you would just need to log in using the same account on your Xbox one. Come August (exact date not yet known) Legacy consoles and current consoles will be on two progression paths and no longer share the same progress. [u]BUT[/u] You can still transfer, once you load Destiny on your Xbox one you will be prompted by a one time service that will ask if you wish to port your characters, once this is done you will no longer be able to hop to and from both consoles and keep the same progression. It'll be like having two different accounts. There is no known limit on how long you can wait to upgrade, as far as we are aware there is no end date right now and all players who upgrade after August will be given a one time prompt.