You should be interrupting your puppy each time he even LOOKS at something he is not supposed to. You can't let it get to the point of nose in the plate, etc.
You need to help the puppy have some respect for you, as he clearly does not.
I would first target train the puppy. Put down a mat or a bed, put the puppy on it, and say "get on your bed". Each time he moves from the bed or mat, put him back, and say "get on your bed". Depending on the dog, and how quick and firm you are about putting him back, after a certain number of attempts to move, he will decide to stay on the mat.
He should stay for 15 minutes in the beginning, and work up to 30 minutes.
Then when you have dinner or guests over, use the target. He will need more prompting when distraction is present. This is normal. Be consistent, fair, and firm. Put him back EACH time he makes a mistake. Gentle praise for correct behavior, however, this is one exercise I do not reward with food. The dog must stay because I said stay, and he must stay until I release him.
You should practice this every single evening with your puppy, and he should be up to 30 minutes within one week's time.
The next thing is to treat him like a dog when he comes up to sniff your food. Ever see a dog beg from another one? No. Take your cues from them. When he dares approach you when you are eating, FREEZE. STARE. Sit up tall. Lean in towards the dog with hard direct eye contact. With your bouncy enthusiastic puppy, you might have to show your teeth, and growl or snarl to get his attention. One he notices your obvious displeasure, keep the pressure on him. Keep staring. Sitting tall. As he loses his confidence and begins to back away from you and avoid your gaze, tell him to lie down, and release the pressure on him by going back to your meal and not looking at him. If you practice this, you should be able to lay the dog down and have him put his chin on the floor every time you have something that he would like to have some of, simply by looking at him.
Try it, and let me know how it works. In order for this to work AT ALL, you must be very serious, and mean it when you look, freeze, growl, or snarl. If I show my teeth to my dogs, they leave the room.