I think of a 5 month goal as being more of a long term goal than a short term. It's hard to know where you'll be in 5 months, and how fast your body will adjust to losing weight.
I would suggest setting one month goals. Since May is starting next week, set a goal to lose 6-8 pounds in May. Then when May in finished you can set another goal for June based on how you did in May.
I made a goal to lose 5 pounds in March, and I lost 6 so I was really happy. Now my goal is to lose 5 in April, and I am currently at 4. One more to go!
This is just my idea.