So how would I go about training our dog to stop instantly like this using "Wait" or "Stop"?

He is quite good when on the local playing field, and won' wander too far without checking I am following.

But if there is a dog he doesn't know, I'd like to be able to shout/say something when he starts wandering to make him stop instantly.

Tips please! And I'll start training him tonight

We use 'down' with Ringo and 'wait' with Finn, so not to confuse either of them

I taught my boys on a very long line, initially in the garden. I use "Down" in an urgent voice and they both drop and stay until I walk to them. Progressed from there out on walks - still on lead, to eventually off lead. Great satisfaction when it all comes to fruition - good luck x

I use a gundog whistle for distance. One blast is 'STOP and SIT NOW' She is about 90% accurate on whistle and will remain stationary until given the recall whistle or a directional whistle.

I got my dog to sit when i ask it by, when mine was a puppy when ever she sat down by herself i said sit firmly and also when your playing with your dog stroke there back and VERY gently push down and when she touches the floor say sit.