AusBonsai

I just obtained this lovely jacaranda with 3 trunks and am unsure how to proceed with starter plan for it, I will study pictures of full grown trees to get an idea of how they look.

Jacaranda are difficult to style as bonsai because of the very large bipinnate leaves. They are reasonably hardy so should be easy enough to keep in a pot and trim and shape. Just not sure how to allow for those big leaves.

How you proceed will depend what you want to achieve with the tree. Many beginners are happy to just have a trunk with some branches in a pot.
To achieve that you can simply trim any shoots that grow long. Pruning should make the tree branch out with extra shoots that can become branches and canopy. Feed it, water it and trim as required. Remove anything you don't like the look of and encourage the parts you do like. Better to leave it in a larger nursery pot for a few years of development as putting any tree into a small bonsai pot definitely slows growth and development. Better to allow some growth while developing the branches and trunk and then switch to a bonsai pot in a few years but if you must have a 'bonsai' sooner you can transfer it to a suitable pot. Just be warned that growth will be slower. Too cold down here for jacaranda so I don't have personal experience with timing for root prune and repot. Hopefully someone else will post some info for you.

Others expect a bonsai to look like a miniature version of the real tree. That will be harder to achieve with this jacaranda. We often let out developing trees grow free for a year or 2, even if they get to 2 m tall because that thickens the trunks quickly. Then chop way down to a stump and wait for new shoots to grow that will become a new trunk and branches. This path can still take 5-10 years to develop a good tree. Good bonsai is not for those without patience.

Thanks for that, I am happy to watch this beautiful little tree grow out for a year or two and gradually begin to see it's potential, atm I am buying starter plants but soonish I will be investing in trees that are already in a bonsai pot for the display value of those, messing around with small plants and watching them grow is a different dimension of enjoyability and creativity with this fantastic hobby.