How long do I have to wait after opening the YouLift Mattress to sleep on it?

This applies to the YouLift Mattress.

You can sleep on the YouLift Mattress immediately after unboxing, as it begins expanding right away. However, it may take a few hours to reach its full shape and firmness.
For the best comfort and support, allow the mattress to breathe and expand for several hours before first use.