2 weeks until school starts

Both girls will be in school this year. Avery seems excited about going back, I just hope we've worked enough on the talking to other kids situation. She's had a few playdates over the summer and she's had no problems, she's even said hello to a little girl at the park (trust me, this is huge).

Brennyn, well, she won't have any problems in the speaking department, it's the sitting still and listening area that has me concerned.
I'm really starting to get worried. I know teachers are used to dealing with children who may have learning/behavioural issues (not saying Brennyn has this, but we are starting to wonder).
She just has a difficult time doing what someone asks (I know, what child doesn't). With Brennyn, she gets distracted and curious about everything else she honestly can't stay still (unless it's to eat).
I love my daughter and I really do love this about her personality. It's who she is. She is the most loving, funny, outgoing kid but it can be frustrating.
Time outs don't work, taking toys/privilages away doesn't work (she just forgets about the toy and moves on to something else, bribery doesn't work (not that I ever bribe my children, never, okay, maybe once or twice), consequences don't work. She just gets into the moment of an act and it's like she can't help herself (for example she ripped up a book, and when we asked why she would do that she said "I wanted to").

Let's just say it's going to be a very interesting year!!