Only apx half of all infants have digestive systems ready for solids by 6mo. Most are by 9mo. Very few *aren't* ready by a year. Actually, that was the old rule of thumb (before formula, and the need to get babies off of formula as quickly as possible -because formula back when was dangerous and even less nutritious than table food-). Babies were traditionally given their first table food on their first birthday. It was usually cake or pudding. It's becoming the 'new rule' as well... as we learn more and more about neural development. We saw the initial switch back toward the old rule about a decade ago (the whole 'breastmilk or formula being the primary source of nutrition until 1 year') and more and more researchers are saying, and new grad peds are recommending not starting solids until after 12mo. There's no need to. Formula isn't dangerous any more, and working mums also have laws now that protect their job if they're pumping.
We did tasting whenever kiddo wanted, but stuck with the 'old' rule, and he had his first real meal on his first bday. Ditto, that's when we started adding solids after formula. AKA eat until full with formula and then offer table food.
At a year, he was perfectly ready. No gas, constipation, fussiness, sleep disturbance, weight loss, or refusal. We did the switch over a period of about 6mo. The bulk of the switch over the first 3 mo and then just continued formula as asked for, and switched to cows milk at 18mo.