Honest opinions!

Oh my goodness is she cute! I think she has time to grow into it, and if it still doesn't fit you could try to pin it from the inside.

How cute! I agree, it's a little bit big, but I think it's ok to leave, because she might grow in those few months, and then it will fit perfectly!

Agree - it's a bit big but looks adorable and doesn't seem to be a tripping hazard. Should be perfect for September

I agree it looks a bit big, at least for the June wedding. Maybe a wide sash made with ribbon (either matching the dress or in a complementary color to the wedding) would help. Since she still, understandably, has "baby proportions" the waist looks super low on her. If you sewed the bottom edge of a wide ribbon to the waist seam, the top edge of the ribbon/sash would hit a bit higher on her little torso and might help make the dress look more proportional to her (if it pulls the skirt up and the waist in to fit her better). Another option would be to see if your alterations person, could sew a small tuck in the bottom of the bodice above the waist seam (on the inside of the dress) to make the bodice shorter and pull the skirt up. She should be able to do it in a way that would be easy to remove if/when she has a growth spurt before your September ceremony. She's adorable either way, but I think some simple alterations might make the dress fit her better both now and in September.