Ds has always refused spoons so we have always given him small pieces to eat one piece at a time. If we give him anything big or give him more than one piece at a time he will cram it all into his mouth and gag. We just put the piece of food on his tray.
The only thing that he has progressed to eating as a whole piece by taking bites out of it is rice cakes, so he has improved a bit.
Now that he is getting older how can we help make the progress to eating normally (with a plate of food in front of him and with him using spoon/fork and eating foods like toast, fruit or sandwiches with one bite at a time).
We are a bit short of space so don't have a table so we can't easily model eating foods with a plate/cutlery, but we do eat things like sandwiches, fruit etc with him when that is what he is eating.
DS used to be like this - I don't know if it's a recommended way or anything but I went for giving him food which was way too big to fit it all I his mouth at once eg I'd cut the crusts off a sandwich and give him it whole rather than cut into quarters.
We also don't have room for a dining table, so we got a toddler sized table and chair set, I sit on the floor on one side and he sits on the chair on the other side and we eat together that way.
If he's refusing spoons, could you try a fork instead - you can spear the food on for him at first, and hand it to him to feed himself?
Our dd is baby led weaned so hand feeds most foods. We always sit up at the tablet, every single meal and she always has an adult eating "properly" with cutlery to watch. She also has a spoon with prongs and a normal spoon. At 18 mo she's getting really good at spooning and is curious about using the fork but when she's particularly hungry or tired she'll hand feed most or all if the meal.
I think, like most things, if you model it and give them the right tools then they want to mimic you and will learn by copying. Didn't teach dd to walk or or play with her toys, I showed her and then let her figure it out in her own time, I guess I don't see cutlery use as any different. I would say 15mo is the right time to start but they are learning loads at that stage (walking, speaking etc) so the fine motor control can take a bit of a back seat and I don't expect dd to be really competent until she's around 2.
I think it just takes time so let him figure it out for himself. Until recently DD (16 months) would only eat if we put the spoon/food in her mouth, if we let her pick it up or gave it to her...it was fed straight to the dogs!