For APL I started with the Mastering Dyalog APL book they have for free on their website which is good, but long. Someone recommended an ancient book I found on Amazon called "APL An Interactive Approach 2nd Ed." I think by Gilman and Rose that is very easy to follow. There are plenty of tutorials online now too (a lot more than when I started looking 8 years ago).

For J, I read a good bit of "Numerical Programming in J" or something along those lines. I've found J to be more difficult than APL or K to pick up tbh. The tacit trains is just a bit too hard for me to follow.