CBSE has released the CBSE 12th date sheet 2020 for all subjects on December 17. The main exams will begin on February 15, 2020. CBSE Practical exam will be conducted between January 1 and February 7, 2020.
As per CBSE 10th Time Table 2020, exams for CBSE Class 10th will start from 15th February onwards & will over on 20th March 2020.
Link - 10th Board exam schedule
Link - 12th Board exam schedule
All the best !
Team - my school