I lived in Brazil for a while and saw many a Jacaranda tree. They sure are beautiful and I do know that some have been made into bonsai, albeit very large bonsai. If I were you I would just keep growing out that tree, trying to get as big and interesting of a trunk as possible to offset the large leaves. Maybe in 15-20 years you can have a good base to start working towards leaf reduction and ramification.
One concerning thing is that many sources I have read seem to say that Jacaranda does not like to flower when constrained in a bonsai pot.
I took this photo from a forum in Spanish. According to the poster, it is a true Jacaranda bonsai, not a Brazilian Rain Tree. The poster lives in Mexico and says that it has never flowered, despite being quite old.
From the same thread, proof that Jacaranda can flower in pots.
To be frank, I would grow Jacaranda to enjoy its form, beautiful bark and leaves rather than its flowers, much like a Crepe Myrtle bonsai.
Fortunately, when given the right conditions these trees are absolute monsters. They backbud like crazy and get beautiful bark when old.
Hopefully I was able to give you some useful imput.