Item arrived earlier than expected so I had to leave it in the box for a week before letting it rise. Once opened I waited the full 48 hours to sleep on it (although one of our cats slept on it anyways). Rose to just over 12 inches. I’ve been sleeping on it for a week now and this bed is great. It’s a little firmer than I thought it would be, but my back feels amazing. Will update in a month or so to see how it holds up.