how long for 4 day old 10 gal tank to be ready?

Tyyrlym

A word on a QT tank, it doesn't have to be fancy. My QT tank is a clear rubbermaid bin, I used a sponge filter, a heater, a left over light from an old tank, and terracotta pots for decorations. Heck you don't even really need a light. With a tank the size you have its hard to recommend a QT. The first batch of fish added to a tank don't need a QT (there's no one else in it to give anything to) and with a ten gallon you're not going to add much more beyond that. Now if you ever move up to a larger tank I'd recommend getting a QT set up, heck, you could use your ten gallon.