If you look up Animate in the help file, you'll see that it has a Transition field which allows you to specify an amount of time which it should take to transition from the current stance into your new animation.
Animate entity,[,mode][,speed#][,sequence][,transition#]
transition# (optional) - used to tween between an entities current position rotation and the first frame of animation. Defaults to 0.
Animate entity,[,mode][,speed#][,sequence][,transition#]
transition# (optional) - used to tween between an entities current position rotation and the first frame of animation. Defaults to 0.