Which file do they work on first? Is the 129f first or I130 first? Thanks.

With all the problems people are having with the K3 I wouldn't even file the it at all!

what re the problems people re having with k3?

That does not quite answer my question. Let me try rephrasing it: My I130 was filed in June and K3 was filed in July. As soon as my file is assigned to an officer, which one would he work on first? Thanks.

Once the petitions are paired together the procedure is to approve them both at the same time. After aproval the K3 is forwarded to NVC and the I-130 is retained for Ajustment Of Status (AOS).

For one not being able to get their GC or SSN promptly.
Some still waiting 6 months + after AOS interview.
Time for applying for US Citizenship doesn't start until the date of GC approval.
Helps having EAD but some employers want to see the GC.
Cost now of $1010 for AOS doesn't help much either.

CRs get GC and SS card in the mail shortly after arriving in the US.

I called USCIS yesterday and the one that I spoke with told me that, they go with the received date. I told her the truth that I foled my I-130 back in may, and she told me, that I need to wait atleast 27 more days before inquiring. She told me that even it appears online that they received my I-130 June 1, it doesnt matter, They would still go with the original breceive date which is May 15. She even told me that I can get my approval sooner for my k3 visa because of my I-130 date. So that means, they go with the I-130 date.

I really don't know, but she really confirmed that to me, I don't know, they gave us different information but I really hope and pray for our approvals!
I hope this answers your question. I filed mine close to yours. checked my timeline

SO do they talk to non-U.S. citizens? I am yearning to call them too.