When your dog gains confidence, you will notice an increase in speed. When he shows you he knows what he's doing, you can remove the touch stick if you're using one, or the motivator. When the dog is racing through the weaves without being asked to, then you can add two more poles. Always add poles in increments of 2. Once the dog is working comfortably through six poles, add two more, until you build up to fourteen poles.
Dogs build muscle memory by doing the same number of weave poles all the time.
If your dog is used to doing fourteen, it will not be as likely to pop out early on a set of twelve in a competition. Once the dog is performing a full set of 12 or 14 off set weave poles quickly and with confidence, you can begin to move the poles in by an inch or so. Repeat the process outlined above, with the wires or guides still in place. Depending on how far about the poles were off-set, it may take several repetitions before the poles are finally in a straight line. Once the poles are in a straight line, you can begin removing the wires or guides.