He's on 4 hours EASY so I just find it odd that suddenly he needs to eat in less than 4 hours
For a while I felt like I was constantly feeding, milk, solids, milk, solids, ALL day long. It passes though. I know it seems odd to feed more frequently than 4 hrs but the solids intake is so minimal at this early stage, just tastes really, that it doesn't really count as a meal. It won't be the equivalent calories that milk offers so is unlikely to impact much or at all on the milk intake for a while. In fact my LO took MORE milk when I introduced solids as he needed a milk feed directly after his solids as well as his regular milk feed! That took me by surprise.
I would offer some solids 1 hr after milk feed, you can just offer once per day to begin with. There's no rush, your LO is still under 6 months, here its recommended to wait until 6 months before starting any solids.
Yes you are correct that the milk feeds continue, reducing at/by 12 months.
Some countries also recommend vitamin drops from 6 months if LO is breast fed. You might want to look into that.