Guess the group by debut date part 1

12345678910111213141516171819202122232425262728293031323334353637383940
Across
  1. 4. 29/03/2007 (girls)
  2. 7. 20/05/2024 (boys)
  3. 9. 18/06/2014 (girls)
  4. 10. 26/05/2015 (boys)
  5. 11. 21/03/2012 (boys)
  6. 12. 03/08/2017 (boys)
  7. 15. 30/11/2020 (boys)
  8. 17. 19/08/2006 (boys)
  9. 19. 22/01/2024 (boys)
  10. 22. 14/04/2020 (boys)
  11. 23. 12/01/2026 (boys)
  12. 26. 06/05/2009 (girls)
  13. 27. 30/05/2023 (boys)
  14. 28. 19/04/2011 (girls)
  15. 29. 23/04/2011 (boys)
  16. 31. 25/03/2018 (boys)
  17. 34. 18/08/2025 (boys)
  18. 35. 09/06/2010 (boys)
  19. 38. 25/05/2008 (boys)
  20. 39. 07/09/2015 (boys)
  21. 40. 20/01/2025 (boys)
Down
  1. 1. 07/08/2017 (boys)
  2. 2. 05/08/2007 (girls)
  3. 3. 12/02/2019 (girls)
  4. 5. 26/05/2026 (boys)
  5. 6. 10/02/2007 (girls)
  6. 8. 16/10/2009 (boys)
  7. 13. 14/01/2010 (boys)
  8. 14. 10/07/2023 (boys)
  9. 16. 20/10/2015 (girls)
  10. 18. 16/01/2014 (boys)
  11. 20. 07/06/2007 (boys)
  12. 21. 13/01/2017 (girls)
  13. 24. 20/05/2015 (boys)
  14. 25. 24/10/2018 (boys)
  15. 29. 26/05/2011 (boys)
  16. 30. 13/06/2013 (boys)
  17. 32. 04/03/2019 (boys)
  18. 33. 24/03/2025 (girls)
  19. 36. 02/05/2022 (girls)
  20. 37. 17/09/2020 (girls)