Drahthaar's advice is damn solid. Similar to the method I use, but I don't use the half hitch with the check cord. That said, it is also involved. If you have never used a belly band and electricity around birds before, it isn't a bad idea to solicit help from someone who has experience.
I can say that I have done both, let em chase and not let em chase. I will never let one chase again, not to any appreciable amount anyway. Realing them back in (especially shorthairs) is just too damn much work. I haven't seen too many that needed to chase to build prey drive. The breed in general has a TON of drive. I will allow about the same amount of chase that would occor for a normal retrieve (i.e. 30-40 yards). Anymore than that, is unacceptable to me.
I actually like to break the chase (stop-to-flush) before I do too much pointing drills. I use this succession. The verbal whoa command reinforced with the stop sign hand. After that, overlay the belly band (lowest possible setting). Give him a cont. stim. and almost immediately after, give the verbal whoa command. When he stops, stop the stim. If he moves, give him cont stim and another verbal whoa. He has to learn that he can turn the stim on and off. From there I go into stop to flush drills. Run him in the field with a bag of pigeons around your shoulder. As he's checking in release a pigeon. When he starts to chase, hit the cont stim belly band and give the verbal whoa. He's learning stop to flush. After he's 100% on that (give it 1-2 months for the whole process) introduce planted birds. If he creeps, and he will, hit him with the belly band until he plants his feet.
All that said, 6 months is young. I might advise not whoa breaking him for another 4 months or so. Some dogs mature faster, some slower.
Anyway, that's the condensed version of what has worked for me. Lots of ways to skin a cat. And like I said, get some help if this is new to you. The first time I did this was over the course of 2 months with a pro.