[Harri (OP)]

Depending on the age of sources I read, cosmic inflation occurred after or before the big bang. Is it now agreed that cosmic inflation occurred before the big bang and if so does it make a big difference to our original understanding that inflation occurred after the big bang? Also is there a reliable source of information I could access regarding this point?

[Halc]

Is it now agreed that cosmic inflation occurred before the big bang and if so does it make a big difference to our original understanding that inflation occurred after the big bang?

From what I can tell, there is but the one mainstream model which is not ambiguous on the ordering of the epochs. The only difference is semantic: which exact moment in time (before inflation, and how much before, or after it) to assign the label 'Big Bang'.
It is legitimately questionable since time as we know it, measured in seconds and such, isn't really a meaningful measure when describing the inflation epoch. Hence the reluctance to assign 'time zero' to the point at which things were most compact.

[Origin]

Is it now agreed that cosmic inflation occurred before the big bang

That's news to me, do you have a source for that?

[Harri (OP)]

I basically searched, 'was cosmic inflation before the big bang?'  From what I could gather, if I was reading correctly, some sources said big bang before inflation and some big bang after inflation. That's why I asked the question 'is it now agreed that cosmic inflation occurred before the big bang?' And also why I asked for a reliable source of information to clarify just what the answer is as of course some of the sources I was reading could well have been unreliable.

[Origin]

'is it now agreed that cosmic inflation occurred before the big bang?

No, of course not.

Also is there a reliable source of information I could access regarding this point?

https://wmap.gsfc.nasa.gov/universe/bb_cosmo_infl.html

[Halc]

'is it now agreed that cosmic inflation occurred before the big bang?

No, of course not.

Also is there a reliable source of information I could access regarding this point?

https://wmap.gsfc.nasa.gov/universe/bb_cosmo_infl.html

The link is pretty accurate. I've had some from nasa that were dumbed down to the point of being wrong, but this doesn't seem to be one of those.
The article actually seems to support Harri's query about the term Big Bang being applied to an event other than the earliest epoch, or most initial state where the universe was most compact.

The Inflation Theory [...] proposes a period of extremely rapid (exponential) expansion of the universe prior to the more gradual Big Bang expansion, during which time the energy density of the universe was dominated by a cosmological constant-type of vacuum energy that later decayed to produce the matter and radiation that fill the universe today.

This wording puts the label 'Big Bang' on the relatively linear expansion phase that commenced after the inflation.

[Origin]

The article actually seems to support Harri's query about the term Big Bang being applied to an event other than the earliest epoch, or most initial state where the universe was most compact.

I think it is too bad that you are encouraging his misunderstanding.  That is tantamount to saying inflation occurred before the creation of the universe. 
The big bang occurred at T=0.  Our current physics breaks down at a time less than T = sec.  The inflation period started at T = sec.  Inflation clearly did not occur before the big bang.
 

[Halc]

I think it is too bad that you are encouraging his misunderstanding.

But I've seen the community use the term in the same way. It's just a label, and I think the cosmologists put the label where it has always been in the regular big-bang theory, which is the commencement of the (more or less) linear expansion of space. Inflation theory added more before that, and they didn't want to move the label.

That is tantamount to saying inflation occurred before the creation of the universe.

Not even the old big bang theory posited the universe as something created, or its cause. It only posited its evolution from the time when everything was more compact (but never finite in size).

The big bang occurred at T=0. Our current physics breaks down at a time less than T = sec.  The inflation period started at T = sec.  Inflation clearly did not occur before the big bang.

If the label refers to T=0 on that scale, agree. But the nasa site does not seem to use your definition of "big bang occurred at T=0", and I've seem such conventions elsewhere. They perhaps use a different label for it.

Out of curiosity, if physics breaks down at sec, how do they figure that number? How do they know it took that long to get to that point? I'm impressed that the theory is worked out in sufficient detail to account for seven orders of magnitude in age before inflation started. Perhaps that is the time necessary for all the causal interactions to occur before they all become permanently beyond each other's influence.

[evan_au]

Cosmic inflation, before or after the big bang?

Most of the discussion seems to be centered on the Big Bang as a point in time, which can be compared to other points in time.

However, more generally, the Big Bang Theory is about the process which led to the universe as we see it today, which includes various phases such as Cosmic Inflation, production of subatomic particles and production of the current Cosmic Microwave Background Radiation (which took about 400,000 years). Somewhere in there is the mysterious process that gave us more matter than antimatter...
See: https://en.wikipedia.org/wiki/Big_Bang

if physics breaks down at 10^-43 sec, how do they figure that number?

That is when it is predicted that energy levels would have dropped enough so that the 4 forces that we know would have become distinct fields.
- As I understand it, there is theory of how the Electromagnetic & Weak nuclear force would have behaved as a combined entity. https://en.wikipedia.org/wiki/Electroweak_interaction
- But we still don't have a quantum theory of gravity, and gravity would have had a major impact in this environment.
See: https://en.wikipedia.org/wiki/Big_Bang#Inflation_and_baryogenesis