You all know where I was recently with a bunch of fellow TMC'ers. I visited again a few days later. I do not believe they will have volume production in place in July. I do not know how many vehicles they can assemble with prototype parts. I am hopeful for volume production to begin soon.
As another datapoint, remember this report on Gigafactory pack integration:
Tesla Invest $216 Million Into Model 3 Battery Line At Gigafactory
Even if the details and calculations aren't quite right, it is clear that the manual assembly of battery packs is only going to get them so far in the production ramp. The automated production lines have to be installed and running correctly to have real volume ramp.
It may be that Tesla can finish up a bunch of vehicles in July, but I do not believe they will have volume production processes ramped in July. I do believe they will try as soon as they can and whatever doesn't work, they'll do by hand if they can. They will make something work. But volume production is more likely cranking through in Sept or October, and even then only if everything is in place and the parts suppliers don't screw up.
Again, a big win is any volume production process running smoothly in 2017. It makes for a blockbuster 2018. Each month before December where the volume production process comes online is a big win.