tim427

Hey there - in a similar position, April 26 NOA2 / K-1 filing rather than IR/CR-1.  Also sent something to NVC research earlier this week.
 
It seems that this is not uncommon, though it occurs only to some small minority of applications. There are a couple of other threads on this as well, which I found helpful (search NVCresearch etc. to find them).
 
I'm likely going to reach out to USCIS sometime next week if I haven't heard anything by then. Some other users have described favorable outcomes from checking in with them (i.e., the application had not been sent to NVC yet). But it also seems common for USCIS to say they have 90 days to send it along. The NOA2->NVC monthly threads have a nice summary document put together by Greenbaum that includes all of the contact details for both agencies and other helpful tidbits. I'm not sure what creates the randomness in mail and transit times over to the NVC, but that is how it seems to be.

Is it smart to wait a little bit before scheduling? Or does it not matter?
 
Our K-1 petition was sent out from the NVC yesterday (7/9/2019), and the physical shipment has not yet arrived in CDJ. I don't think it has even really left haha. However, our status changed to "Ready" in CEAC as of this morning. We should have the DS-160 done later today.
 
Obviously, we aren't going to get the physical letter for some time, but thinking about going ahead and seeing if it is possible to schedule an appointment. I've read a lot of the posts here that state that you do not need the letter in hand before scheduling, and worse comes to worse, can walk up to the window at the consulate prior to your appointment and have them print you out a letter. But don't want to jump the gun and do anything that gets too far ahead of the consulate (but if the consulate has already changed it to "ready" - I assume that means they have the electronic petition?).

Also...
P3 Letter link  - https://drive.google.com/file/d/1cBWgGJr4a5ay3b4OV28_dC3pgf63ZUr-/view?usp=sharing
Visa scheduling / consulate site = https://ais.usvisa-info.com/en-Mx/iv