If you are unable to get to the United States before the wedding to have your prenup notarized, then you have two options:
Have the prenup notarized at a US embassy located in your country; or
Have the prenup notarized at a foreign notary and then have it later authenticated by a US notary (this could also be at a US embassy or a notary located in the US).
Note: you can have your prenup notarized separately from your partner.
Why does this matter?
Notarization helps deter arguments for fraud around signing a prenup (if your future spouse ever challenged your prenup, having a prenup notarized helps your argument)
Some states require notarization as a mandatory step, and without it, the prenup is automatically invalid.
Make sure this is done before the wedding (prenups signed and notarized AFTER the wedding are invalid).