["I'm planning a surprise party for my brother. I already have all the supplies ready to throw a bash!", "I wouldn't be able to keep a surprise like that!", 'Yeah, I have all the balloons, food and gifts stashed in my basement!']
Sounds like you're ready to go!
I am planning a surprise party for my brother. I bought everything I need already like balloons, food, and gifts to throw the best party imaginable!