Well, I'm not sure if you want a Portuguese or Brazilian explanation. However, that is it:
"jeito" is the way of being, of acting; some skill; appearance and many others meanings.
But in this case, at least in Brazil, when you say "quando te dá jeito" you're meaning: when you finally decide or be able to do it, when you have a solution to your problem and now you are free to do whatever you want to. So, yes, you are right about that feeling. It could mean when it is convenient.