Once you have received your new memory foam mattress, it is best to open immediately. It takes 4-6 hours for the memory foam to expand 90% and could take another 4-6 hours to get close to full expansion. It is recommended to wait 24 hours before sleeping on it, but don’t worry if you can’t.Click to see full answer. Correspondingly, how long does it take for mattress to expand?Please be aware that after unwrapping any rolled mattress will take anywhere between 4-8 hours to expand to 90% of its full size. It can take further 4-6 hours to reach its maximum. We advise that you don’t sleep or sit on it during this time to ensure it has time to fully expand to its correct size.Similarly, how long does it take for Lucid mattress topper to expand? EXPAND. Lay your mattress flush on your bed base and allow it 48 hours to fully decompress and disperse of any odor trapped within the foam. Similarly, you may ask, how can I make my mattress topper expand faster? How to Expand Memory Foam Remove the memory foam from the package within 72 hours of receiving it. Allow the memory foam mattress to acclimate to room temperature. Unroll or unfold the memory foam gently onto a flat surface. Separate the layers of the memory foam. Let the foam sit for 24 to 72 hours. Can you sleep on a mattress topper right away?Well, you can relax, jump, or do whatever you want with your bed as soon as you received it. Using it right away won’t cause any damage but will only speed up the process of expanding the foam. When you lay down on the mattress, the heat coming from your body will cause the memory foam to expand faster.