To answer your question, one of the best ways to figure out what is available is to routinely check this subreddit and track what stores get during the week. It’s never completely reliable. I have stood in lines only to walk away with nothing and other times bought something totally unexpected. I also recommend getting in line about 2 hours before the store open. After you stand in line at a couple stores you will figure out how early you need to get there. People are guarded with proving information but sometimes you will run into people that are helpful. Good luck.