I went a few weeks ago, before the "grand opening". We got there around 12:30 -1pm and the fast passes were being distributed for 4:30-5:30ish. yikes!
Funny enough the stand by line said a 20 minutes length wait. So that was a no brainer we just hopped in the stand by line. Even then, i think we only had to wait 5-10 minutes. Turns out so many people got fast passes earlier in the day, in anticipation, that hardly anyone was getting in the actual line.
I don't know how it is now that everyone knows its open. But you might get lucky like we did. Or you could get a late FP, if you are planning on sticking around.
:edit:
Depending on what time of the year you're going, will greatly change the outcome of arriving at lunch time. We were there in March..around spring break time.it wasn't too busy, but in the summer it will be crazy for sure.