We have a friend turning 4 on Saturday and also my cousin's high school graduation party, both start at the same time. I'm trying to decide which is better, showing up to the birthday party late (it's a BBQ which will be going well into the evening) or just sending a gift. The parties both start at 5 pm, we would probably get to the birthday party around 7. Is this just totally rude and I should drop off her present before?

It's someone we are very close with so I know she personally won't be thrown off if we showed up late (letting her know ahead of time) but does it appear rude to the other guests?