Welcome to the forums.
starting off in a small pot allows you to control the conditions as far as watering and feeding goes. When you have a large pot, its easy to over or under water....
Start with a small pot. If you are using rock wool look for healthy white roots shooting out the bottom before moving on.
If you are using soil. you want just a bit of roots coming from the bottom and the sides. But not to much..
Wait to long and the plant will no longer get bigger. I see people usaully transplanting 2-3 times, with any kind of vegetable grow.
Good luck!
-xxx