Ok, here is another interpretation of this misalignment in announcements. It is a little "out there", but bear with me.
While Elon has publicly set the target date for M3 production at July 1st, 2017, I always translated this to myself as September(ish), with deliveries starting end of October (long validation for the first few batches, working out quality and production issues... we know the deal, Model X ramp process, except, hopefully, with much less trouble).
Yesterday Tesla said volume cell production started at GF1 for TE and will start for M3 in Q2. Now, once again, I translated that to Elon-time, meaning, second half of June, with enough stockpile of cells for that September production start of M3. But that too was a little odd to me, I mean how much in advance do you need to start spitting out cells. 2-3 months, really?
So what if Panasonic's comment was a little bit of a slip-up? At this point TE cell production is probably a fraction of what M3 cell production will be, so what if by April, Pana was referring to M3 cells?
The implication of that would be huge. If they actually started volumes for cars in April, that could mean they anticipate vehicle production much sooner than September. Dare I say, around the actual target date (for a change)? This would also coincide with recent reports by Fred, that suppliers say Tesla is Hell-bent of getting all ducks in a row by July 1st.
So if they started "pilot" M3 production in July and actually ramping in August, that would give them almost 2 quarters of production. Meaning, we could be looking at the 100k+ M3 numbers this year that Elon was predicting. Hmm...
Let's not forget that ramping cell production is a lot simpler than ramping car production. Likely that Panasonic only needs to replicate the production line that is now producing cells, especially true since they have similar, if not identical, production lines making 2170 cells in Osaka. We should expect a rapid increase in 2170 production in Gigafactory1. Seems likely that cell production will not limit the ramp of Model 3 production.