Upon receipt of the approval notice, it is extremely important that you review the I-797 for any mistakes regarding names, dates of birth and countries of birth. Also double-check the approved classification period. The best way to avoid mistakes on the approval notice is by reviewing the receipt notice and contacting USCIS while the petition is pending to request corrections. If the mistake is the result of a USCIS data entry error, then the corrections will be made quickly and should not result in any significant delays in obtaining the visas from the Consulate. However, if the mistake on the part of the petitioner, then USCIS will generally not make the correction, instead forcing the petitioner to file an amended petition.