To "accompany", the derivative immigrant must enter the U.S. with the principal alien, or enter within the subsequent six months as described below:
Quote Quoting 22 CFR 40.1(a) - Definitions.
(a) (1) Accompanying or accompanied by means not only an alien in the physical company of a principal alien but also an alien who is issued an immigrant visa within 6 months of:

(i) The date of issuance of a visa to the principal alien;

(ii) The date of adjustment of status in the United States of the principal alien; or

(iii) The date on which the principal alien personally appears and registers before a consular officer abroad to confer alternate foreign state chargeability or immigrant status upon a spouse or child.

(2) An “accompanying” relative may not precede the principal alien to the United States.
The principal alien may request follow-to-join benefits for qualifying relatives who did not obtain residence by accompanying the principal alien.

You should soon be able to pay the immigrant visa processing fee.

The application form that you submit to the Consular Electronic Application Center must include your name, date of birth and place of birth exactly as listed in your passport. If you used an incorrect name or made a spelling mistake on your application, you will need to re-submit your application.

Have your parents read this.