JJtheJetPlane

Your case is different as you are adjusting from a tourist visa, meaning you filed an I-130 with the I-485, so what you sent is the required evidence. It was not front loading. 

These are things you should be prepared for ahead of time. Be settled in a job, be settled where you live, and then, only then bother dealing with immigration stuff, Moving, job changes, ect, only complicate and stress the matter.

You have to give them your employment history when you fill out the application so it has no affect with your situation. Same goes for address history, it has no bearing on the application if he recently moved. 

I hope you make a great salary and your child support payments are very high, I as a man could not imagine abandoning my children over bruised feelings

No as it is actually their first step is to notify you. A few days later your check will be cashed. Suggestion. Try not to overthink this process and everything you see 99.9999% has happened to someone else. And a bad sign comes in the way of RFE's and 221(g)'s and you are way to early for any one of those to arrive to your mail box. I'm just keeping it real for you.

You start the process by mailing a petition package for your husband and one for your baby to an address in Chicago.  You can use DHL or FedEX.  Start preparing by clicking on the word "guides" at the top of any page of this site.  Then carefully study the applicable forms AND the form instructions. (Download both from the same page.)
 
Once you've done the homework, we'll be here to answer remaining questions.

Unfortunately your husband has put himself and you in a very bad situation.  I'm not sure which country you are from but in Pakistan cases likes these have become an epidemic.  Your husband is going to have an extremely difficult time (if not impossible) bringing you to the USA and may not be staying long himself considering the laws he has broken while in USA.    The embassy is very well in tune to men traveling back and forth between USA and the home country impregnating a second wife for several years then "attempting" to file for her after divorcing the USC wife.   This is the very reason my husband and I have had to prove over and beyond that he is divorced from his ex wife.  The embassy drilled the facts above in my head over and over which sucked at the time (because I was not aware how often this happens) but it has since made me 100% more confident in my marriage and our relationship stronger.  
 
The best bet would be for your husband to move back to your country be with his family and raise his children.   I'm afraid it's the only sure-fire way you'll be able to have the "real" family you desire.   Although Polygamy may be your religious or cultural practice it's not legal in USA and if he wished to participate such practice he should not have done so attempting to become a USA citizen.  
 
Sorry that you and your children have to go through this hopefully you'll find a solution that works best for you.  Allah knows best!
 
 

I just got back from Vietnam and the interview with my fiancee. The single status paper is definitely not needed! 
 
Happy to say we got approved very easily! Thanks everyone on VisaJourney and especially @frontgear and @Nle!!! Review will come shortly. @CharlieTshiab if you have any questions feel free to message me any time!

It's not an invitation letter but rather a one-page letter that they called Packet 3.
 
You will need that letter for vaccinations and med exam as per one of my earlier posts here.

For checking the status of your visa, you should select IMMIGRANT VISA (IV) and not NON-IMMIGRANT VISA.
We just recently completed the interview on June 8, 2018. Below is my timeline for your reference.
Prior to receiving the email with the one page invitation letter (Packet 3) from the U.S. Consulate General , I completed the DS-160 and I-134; registered an account at http://ustraveldocs.com/vn/index.html?firstTime=No, paid the visa fee and scheduled the interview. Please note that interview can only be rescheduled one time without incurring additional fee. I did not encounter any visa processing issues with completing these items before receiving the invitation letter.  
 
Consulate :Ho Chi Minh City, Vietnam
I-129F Sent :2017-09-01
I-129F NOA1 :2017-09-06
I-129F RFE(s) :2018-03-16
RFE Reply(s) :2018-03-26
I-129F NOA2 :2018-04-11
NVC Received :2018-04-27
Date Case #, IIN, and BIN assigned :2018-04-30
NVC Left :2018-05-09
Consulate Received :2018-05-11
Packet 3 Received :2018-05-14
Packet 3 Sent :2018-05-15
Packet 4 Received :
Interview Date :2018-06-08  Submit Review
Interview Result :Approved

You will need the confirmation page of the interview appointment in addition to the Packet 3 letter for both vaccination and medical exam, which cannot happen until you filled out DS160, paid Visa fee, and scheduled your appointment.
 
Btw, I've just updated my earlier post with links to the CEAC website.
 
Here is the K1 instructions in case you have not seen it already. Packet 3 is just a single letter with your HCM-XXXXXX number and a link to this same document.
 

What you can do is watch your status on the CEAC website. When it says READY, it means the file has been sent off to the US Consulate in Saigon.
 
What you can also do is contact the US Consulate in Saigon (via their online inquiry page -- link below) with your HCM-XXXXXX number, asking if they have received your physical file. The Consulate normally receives the electronic version first and the physical comes a week or two later. Once they have your physical file, they will mail your Packet 3 within 3-4 weeks of receiving the physical file. If you have not heard from them after 3-4 weeks, go back to the Online Inquiry page and ask them to email you a copy of the Packet 3.
 
I would wait until the Consulate has received your physical file before trying to fill out the DS160, pay Visa fee, and schedule the interview.
 
Vaccination and panel medical exam cannot be done until you have received a copy of Packet 3 letter. 
 
Online inquiry page:
https://vn.usembassy.gov/visas/immigrant-visas/immigrant-visa-inquiry-form/
 
Here is the link to the CEAC website to check your case status:
https://ceac.state.gov/ceacstattracker/status.aspx
 
You want to select NON-IMMIGRANT VISA and VIETNAM, HO CHI MINH CITY on that CEAC page.

My bad. just noticed it

Here are the K-1instructions for processing your visa through Vietnam https://drive.google.com/file/d/1jdCPXg9_vLnAfKJZ5gfPMW4-ST0RbRUh/view?usp=sharing
 
There is an active sub-forum for Vietnam found here http://www.visajourney.com/forums/forum/136-vietnam/ This where others that are processing a visa from Vietnam meet and help each other as that entire group is or has processed at the Embassy in Vietnam. Those that are here are trying to get there arms around their process and more than likely can't answer your specific questions, as each Embassy's process can be and in most cases are different from yours.