She looks over sales records. Is the shop's patronage still growing quickly enough that she'll probably need four employees sooner or later?
It may be time to look into getting a second storefront. Or at least a bigger workroom. Is the place next to the herbseller she originally disregarded still open?
She takes half a day to walk around the city again, incidentally visits the slave market and unbinds tattoos, and looks for someplace with a nice big workroom, preferably cheap.
She asks the building owners if they'd mind her putting in a larger, openable window in. She plans to use her embroidery to lift heavy, bulky things in and out of the workspace. And she offers to increase her deposit a sufficient amount to undo it once she leaves.
When she installs the window, she's very careful not to touch any of the structural beams. The strongest of her new employees is assigned to spend a whole two days hauling tools, jars, and so on over to the new place. Furniture, she buys and transports herself. The storefront near the central market gets converted completely over to just selling things.
She keeps up Aya's lessons. By now she knows enough that she can do most of the not-inherently-magical parts of medicine making, like making empty pill shells and preparing mixtures for magical processes. This (along with trying to think up more efficient ways to make things, or ways to use byproducts) becomes most of her work.
Taxes come due, which eats through a significant chunck of her savings. But she's doing a brisk business and expects it to just get brisker, so she's not really worried that all this expense knocks her stored money down to 400 seo.
The employees have to pay taxes too - Aya already knows how to handle it, since she did her former mistress's accounting, and helps the others. Aya moves to a different boarding house - she'd already switched to a different room after Steel made the extra space redundant and stopped paying for it, but now, feeling stable in her ongoing income, she's closer to the workspaces with a better kitchen and a room to herself.