How should I break in this firm mattress?

Expect a short break-in. A new firm mattress feels firmer than the showroom floor model, which is softer from constant in-store use, and it eases slightly over the first few weeks as the comfort foam and latex settle. Sleep on it nightly and give it two to four weeks before judging. The natural latex layer stays responsive throughout, so the surface loosens to its true feel rather than going soft.