You have to manually massage the appointments to increment to the next year; and you do this in the prior year software (2019 in this case) as that is where the organizers are generated. You then 'bridge' the appointments to the 2020 software so you can follow the appointments during the 2021 filing season as clients/client info arrives.
OR, create the appointments as recurring appointments - those DO increment year by year. But they (recurring) don't notice that appointments will end up on Saturday & Sunday, so some massaging is still needed. Unless you do see clients on the weekend.