How to stop responding to a shake before a button

i am currently making a iPhone app, and a animation reacts to a small shake, this is my code:

static BOOL SJHShaking(UIAcceleration* last, UIAcceleration* current, double threshold) {
double
deltaX = fabs(last.x - current.x),
deltaY = fabs(last.y - current.y),
deltaZ = fabs(last.z - current.z);

return
(deltaX > threshold && deltaY > threshold) ||
(deltaX > threshold && deltaZ > threshold) ||
(deltaY > threshold && deltaZ > threshold);
}

- (id)initWithFrame:(CGRect)frame
{
if (self) {
    // Initialization code
}
return self;
}

-(void)awakeFromNib{
[super awakeFromNib];
[UIAccelerometer sharedAccelerometer].delegate = self;
}

- (void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration      
*)    acceleration {
if (self.lastAction) {
    if (hasBeenShaken && SJHShaking (self.lastAction, acceleration, 0.7)) {
        hasBeenShaken = YES;
        animation.animationImages= [NSArray arrayWithObjects:
                                    [UIImage imageNamed:@"Frame01.png"],
                                    [UIImage imageNamed:@"Frame02.png"],
                                    [UIImage imageNamed:@"Frame03.png"],
                                    [UIImage imageNamed:@"Frame04.png"],
                                    [UIImage imageNamed:@"Frame05.png"],
                                    [UIImage imageNamed:@"Frame06.png"],
                                    [UIImage imageNamed:@"Frame07.png"],
                                    [UIImage imageNamed:@"Frame08.png"],
                                    [UIImage imageNamed:@"Frame09.png"],
                                    [UIImage imageNamed:@"Frame010.png"],
                                    [UIImage imageNamed:@"Frame011.png"],
                                    [UIImage imageNamed:@"Frame012.png"],
                                    [UIImage imageNamed:@"Frame013.png"],
                                    nil];

        [animation setAnimationRepeatCount:1];
        animation.animationDuration = 1;
        [animation startAnimating];
        [self performSelector:@selector(didFinishAnimating) withObject:nil     
        afterDelay:1.0];
        bottle.hidden=YES;


        NSURL *url = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/champagne   
        animate.wav", [[NSBundle mainBundle] resourcePath]]];
        NSError *error;
        audioPlayer2 = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
        audioPlayer2.numberOfLoops = 0;
        audioPlayer2.volume = 1;
        if (audioPlayer2 == nil);
        else
            [audioPlayer2 play];
        [audioPlayer3 stop];
        back.hidden = YES;



        } else if (hasBeenShaken && !SJHShaking(self.lastAction, acceleration, 0.2)) {
        hasBeenShaken = NO;
        }
        }

        self.lastAction = acceleration;
         }

        /*
        // Only override drawRect: if you perform custom drawing.
       // An empty implementation adversely affects performance during animation.
         - (void)drawRect:(CGRect)rect
       {
       // Drawing code
        }
        */

        -(void)dealloc{
       [UIAccelerometer sharedAccelerometer].delegate = nil;
        }

On the same view controller I have another page before the animation, now I need them to press the button 'start' and then they can shake, but before they press 'start' if they shake, nothing would happen. How would I do this?

Just have a variable that gets set when they press the button. Then in the method that determines whether a shake has taken place, first check whether the button has been clicked.

For example, in the didAccelerate method, you could first check if the button had been pressed, and if not, just return.