So my wife and I recently purchased a new latex mattress. It is all latex, a 6" core with 2" layers on either side. We’re very happy with it, but after a few nights my wife feels it is just a little too firm. We did specify a sort of medium firmness when we bought it, but sometimes it’s difficult to know exactly what firmness you need. I’m going to try and see if I can obtain the ILD numbers from the manufacturer so we have that as a baseline in the future.
With that said, I believe adding a soft topper to the mattress will be the best approach to easing my wife’s aches when sleeping on this. I don’t mind myself as I’m pretty flexible on the firmness. But I’m reluctant to purchase a latex topper seeing as how the mattress is already latex. I would need something that is toward the soft/plush end and I’m guessing most latex toppers don’t do this. So if you try to imagine a mattress with a 3" thick pillowtop (which is almost always foam) that is along the lines of the kind of topper I’m searching for.
I would give this more than just a few days because your experience will probably change over the course of the first month or so. The mattress will go through some degree of softening as the materials and components break in and you will also go through an adjustment period. I wouldn’t consider any changes until at least 2 or 3 weeks.
All materials including latex comes in a range of firmness and softness options so the choice of material would normally be based on personal preference while the thickness and softness would depend on your height and weight, your sleeping positions, your subjective perceptions, and on how far from your “ideal” you believed you were. If after a few weeks you still think you need some additional softness, then an extra inch or two of latex (or another material) that is similar to or softer than your current comfort layer will probably be fine. An inch would be “a touch to a little” extra pressure relief and softness while two inches would be “a little to a fair bit” and 3" would be a “fair bit to a lot”. The thinner the topper … the less risky it would be for alignment. How close you are to your ideal can involve some very subjective descriptions and guesswork.
The merchant or manufacturer where you bought the mattress may also provide options for adjusting the firmness of the mattress.
More information about your body types and sleeping positions along with the specifics of the mattress would also be helpful but overall I would wait for 2 weeks as a minimum (and a little longer would be better) before considering any changes and then I would first talk with the retailer or manufacturer of your mattress to see what options they provide (if any) before considering other options you may have such as a topper.