Immediately expanded when taken out of the bag. The quickest mattress to expand that I have ever had. It was instantly ready to sleep on. It’s SO COMFORTABLE. The most comfortable mattress I’ve ever bought. My boyfriend snores and he was silent all night! I think he is finally getting good sleep for the first time in years. I love that it keeps you cool, even when a sheet over the mattress. I love that it isn’t too soft or too firm. I was sore going to sleep in it for the first time and when I woke up, my body felt at ease. It was easy to wake up and get out of it. I’m happy!