I started my son spin fishing when he was around 6-7. Started fishing Caney Fork with red-worms. Then he graduated to fishing rooster tails and trout grubs. When we would go to the smokies I would spend one afternoon with him on the children streams in Gatlinburg. When he was 10 I started him on fly-rods, he would still revert back to the spin tackle. Then when we was 14-15 he noticed that I was catching more fish, and couldn't understand why. Son! for the past 8-9 years I spent most of my time taking care of you and not really fishing myself, now that you are older I can spend most of my time fishing. He also noticed that with the fly-rod I could out fish him in most cases. From that point on he has been purely a fly fisherman.
I would never trade those early years, yeah I didn't get much fishing done, But you know 8-10yrs is a short time compared to a life time of fishing I have left. I just take longer to recover from a rough trip now. At some point I am sure he will have to take care of me on the river and not get much fishing done his self.
Don't be afraid to use spin tackle, it is easier for them and a red-worm, where bait fishing is allow is a sure way to keep them reeling in fish. the fly rod will eventually come.