I need help preparing for my presentation on Friday.
I could help you with that.
Are you sure you have the time?
I promise you that I have the time to do this. If I didn't, I wouldn't offer to help.
What would be the best time for you to help me?
Tomorrow night would work for me.
Should we just meet here?
OK, and I'll bring some information that helped me with my presentation.
I'll see you then.
See you tomorrow night.