I wouldn't bother with Solid Starts, I think it is really overengineered and anxiety-inducing. Or if you do, just take it as suggestions not gospel truth.
You should keep offering in various formats, but no stress if he isn't into it. Keep breastfeeding/formula the same.
It's very very early days and I wouldn't be jumping ahead to 12 months because that's an entire lifetime away for him (literally). It's not literally true that they don't need any food at all until 12 months old, but if you start thinking of it like a deadline that he needs to have eaten food by, then it will stress you out and that's not helpful. Just go week by week at the moment.
Is he bringing objects to his mouth to chew on them like toys etc? And can he sit stable when given support e.g. in a pushchair, highchair or on your lap? If he is not doing these things, it might be worth asking GP/health visitor to have a look and check up on his milestones.
In the meantime, try in different settings, e.g. in your lap rather than in the highchair, as a sensory play experience (e.g. offer a raw carrot stick and a breadstick along with some non-edible items for him to pick up and experiment with). Try different times of day - maybe he doesn't want breakfast?
Try putting food near his nose so that he can smell it. Not necessarily something with a very strong smell, but things like mashed potato or steamed carrot or porridge or apple sauce or yoghurt all have a smell for example. Warm buttered toast, roast chicken, cauliflower, slices of ripe pear.
Does he watch you eating or reach for your food when you're eating? If so you could try giving him some of what you're having. Hold him in your lap so he's upright, and try to find a fairly large piece because babies of this age tend to hold with their whole fist and can't yet open the fist to get at what's inside, so you want to think about something they can grasp within their fist which will stick out so they can access the sticking out piece - that's why chip shapes, carrot batons, small triangles of toast work well.
If you want something reassuring to read, try "My Child Won't Eat" by Carlos Gonzales.