I just spent the morning introducing my young horse to poles. He's seen them before as there's generally a pole or two lying around the arena and has walked over them being led.
I lunged him in a circle until he was calm and listening, then my trainer tossed out a single pole and I lunged him at a trot over it. Then added another pole about 3ft apart (you have to adjust them to fit the horse's stride) and trotted him over two poles a couple times. Then repeated but going the other direction. Since he had absolutely no issues (didn't even bat an eye at the poles) I hopped on and walked him over the poles, then trotted him over the poles, then repeated in the other direction.
Now trotting over the poles with me on him, he tripped a few times, he went short, he went long, chinked the pole a few times and so forth, no big deal and we made a HUGE fuss immediately after he made it over them. Literally, my trainer, my kiddo and I were all loudly praising him every time he went over. Oh you should have seen just how proud of himself he was! He figured out the spacing and as soon as he went over smoothly twice, we removed the poles and went on to something else.
Now we went pretty slow because my guy is 4. When I introduced my 7yr old QH to ground poles, within 10 or so minutes, I was trotting her over groups of 3 but this was a horse that had been trail ridden a ton and stepping over things was perfectly normal for her. Literally I rode over 1 ground pole and then on each lap around the arena my trainer just added another, we didn't bother lunging her over them. Just depends on the horse.. I knew for a fact that wouldn't be good for my 4yr old, he jumped 3 ground poles that were left in the arena the other day and I didn't want a repeat of that!