Time of the event

I am currently working on reserving a room and flights to get to Vegas as I would like to know around what time the Event actually starts or around what time people start coming in to check in.

I would recommend arriving early on Thursday.

The event starts on Friday morning at 8:00 am.
You can usually pick up your badge since Thursday, but you can do it on Friday too(there will be a big line though).
It all depends on what games you’re playing and how the schedule turns out, but that isn’t posted until a few weeks before the event.
The rule of thumb is that if you’re planning on entering a game with a potential 1200+ attendants, then you should be ready to start playing on Friday morning.

I’m entering MK9 and Persona 4.

Will I still be able to pick up my badge and stuff around 5-6 PM Thursday? Or should I go for an earlier time?

I would recommend going at an earlier time just so you don’t have to rush. Checking-in can be a very slow process.