I would definitely make sure you have all your gear before you start too. Nothing worse than realizing you need another light or another fan or forgot to get a certain expensive nute that you need to use right away and not having the money to grab it right away.
By the way, not to generalize, but most folks on here are new as well, and they may hand out info that they heard somewhere but don't actually know themselves. So just because someone on here told you a certain piece of advice, you still may want to research it yourself. For example, yes you can sex before switching to 12/12. Most folks on here just don't veg long enough to. I veg for 8 weeks, and yes they are big, around 2 1/2-3 feet tall, but I have room and enough light not to worry. Around week 7 I think it was, most start showing their sex.