How long should I keep my arm elevated after hand surgery?

2-3 days. Swelling achieves a maximum at 2-3 days. Make sure you don't over elevate such as over your head and interfere with circulation. A pillow on you r chest or at your side with your fingers pointed up higher than your elbow and of course higher than your heart no matter what your position is helpful. Ice may be used but not if there are circulation issues or problems.
2-3 days. Elevating the operated hand above the heart will minimize swelling and decrease pain for the first 2-3 days. After that, if you let your hand go below the heart and feel throbbing with every heartbeat, it is best to keep elevating till that no longer happens.
24 hours. After hand surgery, elevating the operative limb for 24-48 hours should be sufficient to reduce swelling. Afterwards, elevation is probably not as clinically important.