Planning A Vacation Months Ahead?

I just made friends with a guy on a dating site (potentially crush) for 3 months or so, and I want to plan a vacation with him in December (It’s now September). I don’t expect to date him yet; at least not this time. Is that okay to do so?
I feel like I shouldnt have asked him that because I have known for 3 months only. Did I screw everything up?