Well, 400 per month was just this month because of that stupid issues where a lot of the recent produced boards had Wifi issues (you might've seen, some even slipped through to customers).
In April it was about 700 boards and as soon as the WiFi issue those board have has been fixed, there will be more boards as well.
Also, Batch 2 is currently being setup, using a new PCB revision.
This revision doesn't add new features, but it improves some areas which had repeating issues (L/R-Buttons, etc.) so that the boards that will have less issues. That should be another speedup.
Next month we'll hope to get a higher amount of PCBs again and after that, Batch 2 should start already, meaning that we should haven even less issues and more speed.