A full month early to take advantage of summer weather?

DD1 will be 4 at the end of September.

We are debating having it at the end of August because we can have pools set up (or at my parents, they have an in ground pool). In addition, it's before she starts preschool - I am a bit worried she'll want to invite 30 more kids if we have it in September?! Ha!

Would you give someone the side eye for having their kid's party a month early (or late)?