Deciding when to slow-play a monster hand involves considering several factors, such as the strength of your opponents, their playing styles, and the texture of the board. Slow-playing is most effective when you’re up against aggressive players who are likely to bet or raise, allowing you to trap them into committing more chips. If the board is relatively dry and unlikely to hit your opponents' ranges, you can safely slow-play to build the pot. However, if there’s a chance that a more favorable hand for your opponents might emerge, you should be cautious and avoid risking the hand by slow-playing too aggressively. Understanding the dynamics of the table and the tendencies of your opponents is key to determining the right moment to slow-play.