After unboxing your Amerisleep AS3 Hybrid, it will begin to expand immediately. Most of the expansion occurs within the first few hours, and the mattress should be ready to sleep on within 24 hours.
However, it may take up to 72 hours for the mattress to fully expand and reach its optimal comfort and support levels. It's important to note that the expansion time may vary slightly depending on factors such as room temperature and humidity.