Use a well drained soil medium with lots of organic matter. Jaboticabas like lots of water. Put the pot on a saucer and keep the saucer full of water for them to absorb all the time. Fertilize every 3 months. They are slow growing plants, but with lots of food and water you can speed them up a lot.
Don't forget that they like a ph as low as 4-5.5 or so...depending on Species. They hate excessive fertilizer, and young plants will be killed easily by a heavy application.
I fertilize mine monthly, but at about 1/4-1/2 of the recommended amount (on the bag of Espoma Holly-tone).
Also don't forget that your tree will fruit much sooner in certain cases if you thin out the larger branches, encouraging more sunlight to penetrate to the caulis, and more flowers to emerge over time...where they are most abundant on most species....the caulis (old wood)....and each node that produces flowers, will increase in productivity...starting out with the first blooms being only 1-8 per node...then over time they can have an excess of 25 or so, individual blooms emerging, per flowering node.
Pruning jaboticabas is not for every grower (those in areas subject to harsh winters should think twice) and definitely not for every species of Myrciaria/Plinia.
But it looks like yours will enjoy some pruning over the years...they appear to be the most common variety on the planet...Myrciaria jaboticaba (Sabara)...and considered one of the premier cultivars.
(PS...what is your soil comprised of? Looks like a nice red/ orange color...I wonder if you purchased them with this soil, or if you added it yourself? Most jabuticabeira seem to enjoy the terra vermehla (red colored earth...with clay and good Fe content) and other organic matter.
Best of luck with your wise purchase.