For the application of this section, the average turnover or the average result is determined:
1° For persons who began their activity before 1 January 2018, by taking into account the period between 1 January 2018 and 31 December 2019;
2° For persons who began their activity in 2018, by taking into account the period between the first month of activity and 31 December 2019. The turnover achieved in 2018 is calculated over twelve months;
3° For persons who began their activity in 2019, taking into account the period between the first month of activity and 31 December 2019. The turnover achieved in 2019 is calculated over twelve months;
4° For persons who began their activity in 2020, on the basis of a forecast amount of revenue for 2020 corresponding to a usual activity duly justified by them.