Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
Wanna do 6pm your time on Thursday? Nothing much to do, just have some teams ready to go and maybe the damage calculator if you wanna run some calcs during the match https://calc.pokemonshowdown.com/index.html
You could also check the tier related forums if you aren't too familiar with it as well