I'm hosting Christmas this year for the first time. I'd like to do a more modern take on a prawn cocktail. I'm a Brit in NY, so want that familiar feel, as I'm also doing turkey with all the trimmings. I've seen shrimp in Marie Rose dressing, served in avocados - and I'm wondering how far in advance I can make these without the avocado browning? Ideally I wanted an appetizer I could make first thing in the morning, and stick in glasses in the fridge until the mid afternoon meal. As I'm cooking for 20 including my 5 small children, time is not going to be on my side! Any other recipe suggestions appreciated, thank you!