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.
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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.
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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.