Nick,
okay here is the problem. For us Ficus does poorly in soils high in organic mixes and normal pots.
I will illustrate below with images after all of this writing.
So my advice might not work on your side.
Still here goes.
[1] Use a shallow pot at about 1" to 1,5" in depth.
[2] Use a soil mix with [ by volume ] 5 shovels of non porous inorganic and 1 shovel of organic material.
[3] A 1/3 strength fertiliser into moist soil.
[4] As close to sunlight as you can get and some form of a light breeze.
A pot about as long as the tree is tall, and very shallow.
[5] Talk to the guys from Florida
[6] Ignore all I have written and ask the guy at Bonsai Brooklyn.
[1] Images, 1st attempt at grow Ficus p. [ looks like the popular one from Florida, but ours is also a proper tree that weeps.]
Disaster, coarse and wounds will require special techniques to heal properly.
[2] Started over in 2009 / 2010
[3] 2015 - 3" trunk and good surface roots - pot at 1" or so deep.
Next refinement of branches.
Tree behaves like an orchid, needs little to live on.
Wounds are minimal and healing nicely.
First attempt back in 1990's
View attachment 93254
second attempt - 2009 / 2010
View attachment 93255
4th year 9 month 2013 - extension branch for thickening
View attachment 93256
November 2015
View attachment 93258