Answer
$a =6.3 m/s^2$
$t = .44s$
Work Step by Step
Both your sister and the turkey will begin accelerating at mg, where m is her mass. This means that the acceleration is given by:
$ a = \frac{F}{m}=\frac{12*9.8N}{12+6.8 kg}=6.3 m/s^2$
The table is .60 m long, so the time you have is given by:
$ x = x_0+v_0t+1/2at^2$
$t = \sqrt{\frac{2x}{a}}=\fbox{.44s}$
