Good to hear he's making the connection. It can take a while it seems for them to come to recognize the lure if its moving. Once they do though, look out because they will be all over it from then on. Its kind of the last real hurdle to get them past. I hope the baggie goes well for you. Make sure he gets it by tethering it or perhaps releasing it someplace where it cannot get away from him. Its better if things progress in a natural manner, with success, than if some opportunity gets missed which can be a setback. You won't likely have to do a lot of baggies as you want to be careful about their use as the birds can get too used to things being too easy to catch. What I usually do is give them about three, then back off and show them some wild slips, and if they don't catch those or worse yet don't chase those, then I go back to the drawing board and offer a bag again to increase their confidence. Sometimes their response can be related to hunger, but it can also be related to development. You can offer all the slips you want and not have them go for them because they just aren't quite there yet in development. They do stay with their parents for a few weeks after fledging, getting support from them in the form of feeding until they are doing on their own. I'm sure that some get lucky and score very early on, becoming proficient hunters. Others may not get lucky from the beginning and struggle for weeks trying to make up for the initial failures. Then one day they get lucky too and their physical and mental development finally mesh to create the killing machine they will be in the weeks and years ahead.
So don't get discouraged, he sounds like he is progressing just fine for his age.