how much weight to loose?

So my goal weight is 125. Right now I'm 136, I'm tall 5'6 almost 5'7. I've never been under 135 so I know 10 pounds isn't that much but it's a big deal for me because this is the first time I'm actually trying to loose weight. But it's hard to weigh myself or be able to tell my weight because my weight fluctuates a couple pounds every day even after I made sure I only weigh myself before I eat or drink anything. Is 5 pounds a week too much to loose in a week? I want to do this the healthy way and not too fast