Twink
PIP awards are supposed to be based on the last three months and next none months so I think you need to mention it on the form, however, you cannot comment at this time on the benefits that you receive from this assistance dog until you actually receive it.
You mention you have a carer so I assume that they currently do some or all of the things that the dog will do. Remember it not about the assistance you get but rather the assistance that you need.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
