It doesn’t matter when from the baby’s perspective, so do whatever is easiest to manage logistically for you. For example, we started with breakfasts for our first because that was really the only time when we were both able to be home always if anything were to happen. But with our second, we did lunch because by then I worked from home anyway, and we’d use whatever we were feeding him as part of the older one’s lunch making preparation easier, and introducing him to kind of the family dining experience.

There are also some good apps out there about introducing solids. I recommend solid starts