More detail
You do not need a big setup to begin. A phone, your prices and a way to take payment are enough for a first sale, and the free terminal upgrades that into a proper counter.
Add your KRA PIN to switch on eTIMS filing, and load the rest of your stock as you go. The aim is to be selling quickly, then build out the catalogue rather than waiting for it to be perfect.
Related questions
Can I start with just my phone?
Do I need my KRA PIN on day one?
Veira gives Kenyan shops one calm app for selling, M-Pesa, KRA eTIMS and stock, with a free terminal. Book a demo and see it set up for your trade.