Telling boss - dilemma - what are you thoughts?

simplein06

I'm in management in a field that is about 30% women.  My direct manager is in New Zealand.  I only see him a few times a year, but talk to him every week.  He is coming to visit for my performance review. The actual raise and rating won't be determined until after he leaves.

I'll be 11 weeks while he is here.  I'm torn on whether I should tell him while he is here so we can spend time discussing all the changes that will need to occur to accomodate my absence.  On the other side, I feel like I'd prefer to wait until the performance rating is determined to tell him.We get along great and I think he'll be very happy for me, (he has an 18 month old), but I'm not sure if it could affect my rating

The other concern I have is that when he is here we normally have dinner and drinks (or just drinks)  I think he is going to suspect something when I'm not drinking. 

what are your thoughts?