I brought my 19 plate Ex CVT a couple of weeks before the 69 plate started and saved circa £2500, against a previous quote a couple months earlier, so it certainly pays to plan ahead.
I can confirm Jocko's comment, the reduced depth spare wheel space was introduced for the 2020My, we think to create a common floorpan with the hybrid version, thus creating space for the hybrid battery.
The same Honda bulletin also states, the Sport version and the colour Sunset Orange are discontinued
So if you particularly want spare wheel space, then you need to get in quick for 1919My vehicle, although I guess at this point in time they will be difficult to find.