How to make a minecraft like texture system!

I have a procedurally generated cube and i would like to add a uv map similar to what minecraft has. I would like to make single texture for like 20 cubes and change them at runtime. Like dirt in minecraft when it turns into grass after a amount of time. How would i modify the uv’s to a certain spot on the texture no matter what size it is? Please don’t just give me a link to the unity script refrence saying look at this, cuse i don’t explain it in a good way. Thanks !

for simplicty run a waitforseconds() script and swap out uvs. you will need to place this in a command that will allow the rest of your script to run with out waiting on the time to finish.