Just got a new memory foam mattress topper and not sure if it will be too hot and unbreathable without the mattress pad.

I bought a kingsize Tempsoma 3" Memory Foam Mattress Topper Friday morning at Sams' Club. It's been over 48 hours and three of the four sides have not expanded. It's only 2 inches on each side. I really want to go ahead and put it on the bed, even tho the packaging says it may be up to 72 hours. I searched the web and only found mention of it being a problem with Costco's Novasoft. Thanks! 72 hours has come and gone and the three sides still haven't expanded. We went ahead and put the velour cover on it and put it on the bed, and truthfully it's not a big deal to us. The side that's expanded we put at the head of the bed, and the sheets smooth out nicely along the mattress topper.

I purchased a dream solutions memory foam mattress topper, It was packaged so tight it was flat when I unfolded it. Laid it out for a day but still it did not puff up. No instructions or number to call in the box so I was wondering if there was something I can do to unflatten the topper

Does anyone have suggestions for getting your sheets to fit over a 4" memory foam mattress topper? Do California King sheets help?