In the lower 48 states, any fig (ficus) should be outdoors in the sun full time till nighttime temperatures hit middle fourties (at night).
Every day a wooden chop stick should be inserted into soil and then withdrawn. When you check the tip that was in dirt it will be,1, damp, do not water today. Or, 2, dry, it will need to be liberally watered.
Your soil looks to be mostly garden soil. Its particle size is too small. You will need soil specifically for bonsai (or cactus).
Figs will tend to shed their leaves if watering or light levels are inadaquate.
Think like a tree
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