Nothing occupies the Project Planning process quite like setting a deadline, usually with software projects this is a launch
When setting a launch date avoid externally committing to a deadline. Where you must externally commit to a deadline, commit to a conservative one you are likely to hit. Create an ambitious/aggressive internal deadline with the team that you are comfortable with missing1.
How to handle a missed deadline
If the deadline was aggressive, punishing or scolding the team is likely to instill a culture of conservatism. Ambition gets punished. Instead, the leader should acknowledge that they understand that the deadline was missed because of how aggressive it was, commend the team for setting an aggressive deadline and indicate that they should continue to do so to maintain an aggressive and ambitious Culture.
1. Doshi. Thread on deadlines and team productivity. Twitter (2024).