Mita Ichi

I filed I-130 for my 3 kids ( all over 21 years old and all single at that
time) when I am holding the GC in 1995. When I became a US citizen a few
months ago, I contacted the INS and had all my cases upgraded. Then I have
paid I-864 processing fees when they requested. Now NVC sent the I-864
forms to fill and to return to NVC. (all of my sons are not in the US)

Here is my situation today:
One of my sons is going to marry next two weeks . I haven't returned any
I-864 form yet.

my question:

What effect will have on his immigrant petition status if I wait two/three
weeks after his wedding and fill his spouse's name in I-864's as spouse
immigrating with him ?

Or any suggestions?

Thanks in advance.