How to use frozen bm?

CatO

I apologize if this is a naive question, but on Sun we are going out without LO for the first time. I just started pumping this week and have been freezing what I pump. I will probably only need to leave one bottle. My question is do I thaw the milk and have it ready to go in the fridge for the sitter or does the sitter need to thaw it and put it in the bottle? Also, my LO will be 8 weeks Monday and I am not sure how much to leave in a bottle ounces? TIA!!