If you want to get in shape before summer, you don't have much time.
Here's what I'd start doing today if I wanted to lose 8-15 lbs of fat before the summer:
1. Eliminate alcohol. These are negative calories because your body burns the alcohol before it burns fat, while increasing appetite and hunger. Removing it will automatically be a net positive.
2. Lift weights using progressive overload three days a week, bare minimum.
3. When lifting weights, focus on full-body workouts so you can hit your muscles more frequently.
4. Aim to lift your weights until you get to one or two reps before failure. This will help you give you a chance at building muscle if you are in a calorie deficit.