What type of mash tun are you using? How will you be sparging? How much does God love you? There are lots of variables in your efficiency. My buddy and I both use cooler tuns with a stainless braid and batch sparge getting around 70% efficiency, people who fly sparge tend to get slightly higher efficiency. Your first time out will be an experiment, it can be anywhere from 50-80%, you won't know until you try...
Primary: Pineapple Heffeweizen
On Tap: Simcoe/Amarillo IPA, Centennial Blonde
Bottled: Milk Stout(bronze and gold medals), Spiced Punkin Ale, White House Honey Porter (ag), Mango Wine, Gerwurztraminer
"If wrong feels so good I don't wanna be right."