Depending on the child for us. DS1 was barely 4 months DS2 7 months, DS3 had some rice cereal in his bottle due to reflux but ate from a spoon about months DS4 somewhere between 5 & 6 months.
The day they turn 6 months does not magicly make them ready. My boys all sat alone at about 4 months double their weigh ( or nearly) actively was grabbing for foods.
I started with purees none of them would eat rice cereal ( its gross if you ask me) Breast milk or formula is the main form of nutrition at that age but we started offering a few bits before 6 months except for ds2 who would spit it at you if you tried to feed him
Jeana, Momma to 4 fantastic sons
Everything happens for a reason, sometimes the reason is you're stupid and make bad decisions