Hi 2bsticks,
Yes … there will be a break in period with any new mattress and it can also take some time to adjust to a new sleeping surface although it will vary with the mattress and the person (see post #2 here).
While in some cases it can take longer … it’s usually a good idea to give any new mattress at least two weeks before considering any changes.
I would also be a little cautious at your weight with a softer mattress because of potential alignment issues.
Phoenix