Forgot to include the form 8958 with my e-filed Federal.

I completed my son's taxes yesterday, and he E-Filed the Federal already after it was completed. I reviewed everything and noticed that I forgot to include the Form 8958 with his Federal return. He received the text stating that the Federal was accepted by E-File. Do I have to amend his Federal now to include the Form 8958?  If so, when do I do the amendment to include it. Thank you.