The UK CAA have sent out a reminder ... this is an extract from an email I received last week:
Flightcrew licence holders who are considering transferring their licence to another EASA Member State are reminded of the advice to apply at least 3 months prior to the end of the transition period (31 December 2020).
Applications received after October 1st will be processed on a best endeavours basis, However, there may be insufficient time for the CAA and receiving NAA to process the application before the end of the transition period, after which the application may no longer be valid in the EU.