请问:(电子化)CR1 P3确认后,多久会收到P4呢?

在这里有一个问题请教你们：
我收到P3已经第三天时间了
Dear Sir/Madam: All documentation necessary to complete the National Visa Center's processing of your case has been received. As soon as an interview date has been scheduled, the applicant, petitioner and attorney (if applicable) will be notified.
.还没有收到传说中的P4呢...我是电子化的
我想请问，你们知道大概多久才收到P4吗？？
在等待，焦急...因为我的公主也准备回来，她要安排时间买机票和准备准备呢.......谢谢噢！！