I can't eat too close to when I go to bed since I got my last fill because I now get some reflux. During your pre op just do your best to get your protein and calories in. When you get them in isn't that important. Do what works for you, your body and your schedule. If setting exact times to eat works best for you, do that and try to stick to it. If something comes up and gets you off schedule, do what you need to do to get by and then get back on schedule the next day.