The NBA season start date depends on the year in question:
- For the 2020 NBA season restart during the COVID-19 pandemic, the regular season resumed on July 30, 2020, in a bubble format, and the 2020-21 NBA season started on December 22, 2020, with a shortened schedule to adjust for the pandemic disruption.
- The regular 2019-20 NBA season began on October 22, 2019, before being suspended and later resumed in July 2020.
- The upcoming 2025-26 NBA season is scheduled to begin on October 21, 2025, with a full regular season planned.
If the question about "NBA season start 20" means the year 2020, the official start for the 2020-21 season was December 22, 2020. If it means the 2020 calendar year, the NBA restarted the 2019-20 season in July 2020 after suspension. Please clarify if a different year or season is intended.