I think one bottleneck that many K1-to-AOS don't realize is the time to receive the marriage certificate (not marriage license).
Depending on which state or municipality, the marriage certificate can take 30 days or more to receive.
We avoided the wait by going to Las Vegas for the wedding where we got the marriage certificate the same day as the wedding.
Also, you can start collecting the documents for the I-864 like the last 3 years of tax transcripts, payslips, etc.,
A couple of other fairly important steps to plan for the K1 beneficiary is opening a US bank account and getting the state Real ID or driver's license, which rely on the SSN and marriage certificate (for name change).
But as a rule of thumb for the super-prepared, if you can file the I-485 within a month after US entry, then you are balling.
You can see the step-by-step of what we did at our Timeline or Profile.
https://www.visajourney.com/profile/386517-eatbulag