The transition period takes effect from January 31st to the end of 2020. During this time, businesses will be able to trade with the EU on the same terms as they do now. There are no immediate changes that will come into effect from 31 January that you need to prepare for. Organics will continue to follow EU rules until the transition period ends, including import/export rules and labelling requirements.
DEFRA have issued the paper below which deals with frequently asked questions on the transition period.