Immediate Eligibility Upon Draft
When a player is selected in the NBA Draft, they become immediately eligible to play in the playoffs for their team that same season. There is no waiting period or probationary time. If a team that drafts a player makes the playoffs, that player can participate in playoff games as soon as they sign their contract and are added to the active roster.
Active Roster Requirement
To actually play in playoff games, a draft pick must be on the team's playoff roster. Teams can add or remove players from their playoff roster before the playoffs begin, so simply being drafted does not guarantee playoff participation. The player must be included on the final roster submitted to the NBA for the playoffs.
No Regular Season Playing Time Needed
A draft pick does not need to play any games during the regular season to be eligible for the playoffs. Even if a rookie sits on the bench all season, they can still be added to the playoff roster and play in postseason games if the team decides to include them.
Standard NBA Eligibility Requirements
Draft picks must meet basic NBA eligibility rules, including being at least 19 years old or one year removed from their high school graduation. International players and college players must also meet these age and eligibility standards. Additionally, the player must have a valid NBA contract with the team that drafted them.
Draft and Sign Process
For a draft pick to be playoff-eligible, they must officially sign their rookie contract with the team. Unsigned draft picks cannot play in NBA games, including playoffs. Once the contract is signed, the player can be added to the active roster at any time, including during the playoffs. 
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