When my DCs were babies, the guidance was four months.
They started on baby rice and baby oatmeal, then moved on to purees. I made my own by boiling and/ or blending veg and fruit and putting it in the blender, then freezing in ice cube trays. They would have one cube with the baby cereal to start.
They also had mashed bananas, but these were prepared fresh.
I added no sugar or salt to any of the fruits or veg I prepared.
The fruits I used were stewed apple, stewed plums, stewed pears, blueberries (just blended, not cooked), avocados (mashed), and mangoes (just blended).
Veg - peas, broccoli, spinach, carrots, parsnips, and sweet potatoes.
They all had CM issues, but they tolerated Greek yogurt well (unsweetened or with unsweetened pureed fruit mixed in).
Some foods went down well, and some didn't.
They graduated to scrambled eggs and very finely cut up fruits and cooked veg by around 6 months. Also bagels, a little peanut butter spread very thinly on toast, white potatoes mashed or mixed with unsalted bone broth. They could manage plain cheerios, and two of the five DCs tolerated little bits of cheddar.