My DD grabbed a strawberry when she was 5.5 months and grabbed my hand that was holding an apple and brought it to her mouth and licked the apple at about the same time. i didn't stop either of these, she had a taste and that was all. We started giving her foods to try at 6 months, but it wasn't until 8 months that she started swallowing food.

I didn't offer any food or deliberately put it in front of her before 6 months (and i think i will do same next time), but if baby grabbed something i think i would just watch and only intervene if it was dangerous or baby was having difficulty. I don't think i actually have an age limit cos their skills will determine their ability to get the food and then work it in their mouth etc