There will be no hard border, ever.
Everyones best endeavours to avoid will be good enough because everyone is singing from the same hymn sheet on it.
Trusted trader scheme, agri checks done at source and at points away from the border and kept to a minimum with filing of relevant paperwork done electronically and in advance will all be brought in on a reasonable time frame.
As discussed an FTA has then too be negotiated and its the time in between that is the worry re WTO and any objections that might arise to the temp arrangements in place but that will have to be a suck it and see wait.