Hi A.,
I have the perfect solution! :) Sometimes I feel like I should write a book with all of my great teaching training. Sorry I get so carried away. ;0)
#1 Have a plan.
#2 Be consistent and stick to it.
Before you ever go, think to yourself what will work for you and him. Set up in your mind and/or write it on paper exactly what you want to happen. So, A) He will sit in his chair correctly. Then B.) what will happen if he doesn't? (know ahead of time) like you are going to carry him out to the car... or carry him to the bathroom, or have a time out pillow with you, etc. Whatever will work for you, but like I said PLAN for any response he may give you. That way you are ready and surprise him instead of him catching you off guard.
Also, in your PLAN come up with positives. I think this is most important!!! Like give him a chart with the opportunity to fill it up each time he sits quietly. Then make sure to really reward him for doing any little good behavior... maybe his first could be from walking nicely to his chair...talking in a restaraunt voice, using good manners, etc. whatever as long as he is immediately rewarded. If he fills up his chart then he gets extra food, or a treat, a new toy... do cheap things like a box of crayons or a new $1 coloring book. As long as you act like it is the coolest prize ever, he will think that too.
You could do a sticker chart or do smiley faces. (If a chart is too much just have some M & M's handy--give one out each time he is good.) Sometimes I see teachers do a chart for one day and have the child try and earn as many sticker possible. Then the next time you go, see if he can beat his record. Again it is focusing on all the positives he is doing.
You can even staple like 5 pieces of paper together and bring it with you for him to draw on while you all wait. Maybe he has to wait to go to the next page until you acknowledge another positive behavior. Even do like a bonus double reward if the waitress notices how good he is.
I would use this system for anything and everything you do... like going to the grocery store, Wal-Mart, church, airport, in the car, movies, etc. As long as you have a plan and stick to it. You will be good. The child learns what to expect and how to be rewarded for good behavior. Obviously it can change as he grows up.
Good luck, sorry again that I write so much! I know your little one is only 15 months, but he understands. Plus this is the PERFECT age to start setting limits and sticking to them. If you think he is old enough, try going over the 'plan' before you take him out to dinner. That way he will know what to expect also and he knows it is his choice.
(one more thing! sorry!) If you do have to do consequences only make time out last one minute. It should only be one minute for their age. 1year-1 min. 2 years-2 min. 3 years-3 min. etc. There attention span is too short. Which is also why it is crucial to do immediate reinforcement (positive or negative) when the behavior occures.
okay I'm done! ;)
Amanda
Let me know if you have any questions.