I take it the dog is being properly socialized?
You could introduce the dog to a quail or a wing clipped pigeon at that age as it will build desire, but I wouldn't overdue it. Still pretty young dog and socialization and bonding is still ongoing at this age. continue to work on some basic commands like "come" or "kennel" or what ever command you wish to use for this. Use a check cord in conjunction with giving the command, but keep the pressure low and make it a fun thing for them. Their attention span is still very short at 12 weeks. You could certainly take the dog for walks or runs in an open field where there may be wild birds as this too is a new thing and part of the learning process.
Most professionals don't like to take a dog in for more formal training or even just entry level bird and gun introduction till the dog is at least 5 months old. they just don't have the attention span yet any earlier.