Yes, there will be definitely some delay between the NOA2 and the interview, just by virtue of the case getting sent to NVC and then to the consulate. But for our timeline, keep in mind this was still during the height of the pandemic when things were moving slowly. And in that 4 months between NOA2 and the interview, the consulate in Mumbai shut down for a month due to the massive COVID surge in late-Spring 2021. Plus, we purposely chose an interview time a month out, because my husband (then-fiance) needed time to get the medical exam, his police clearance certificate, and some other documents.
But more generally, the thing that I didn't realize beforehand is that the interview time isn't assigned by the consulate, but rather, applicants choose the time slot themselves, based on what's available. IIRC, after our application got to the consulate, and once we had submitted all the necessary online forms to the consulate and paid the fee, we were eligible to choose an interview time. As I mentioned, at the time my fiance became eligible for this, the Mumbai consulate was completely closed due to the COVID wave at the time. But once they reopened, they would periodically post interview slots, which any eligible applicant could select, whether they had been waiting 3 days or 3 years to schedule their interview. For better or worse, there was no element of "first come, first served" for scheduling the K1 interview. (For us, this was actually better. Back when I thought the consulate assigned the interview time, I thought it would be "first come, first served," and given the huge K1 backlog at the time due to the first year of the pandemic, I thought my fiance would be waiting at least a year for his interview.)
I should also clarify that the interview times are posted on some Dept of State or maybe consulate-specific website (it's been a couple years, and I haven't had to use that website since then, so I've kind of forgotten what it was, but I'm guessing you might be familiar with it?). I think there's also a phone number one can call to try to schedule the interview, but I found that less convenient than the website.
I found it was best to check the website around the time the consulate in Mumbai opens each day. Sometimes only interview slots a week later would be posted ; my fiance's case, this wasn't enough time to gather everything he needed. At the time we actually selected an interview slot, the interview would be a month later, but there was nothing on the consulate's end stopping us from choosing an earlier interview date.
Hopefully this information is helpful, and not too redundant for what you might have read elsewhere. If it would be helpful for me to explain anything else, let me know! Like I said, it's been about 2 years since we were at that stage, so my memory is a bit fuzzy, but I can try to look up any details that could be helpful.