I have a MH-Z19B that I would like to get talking to my Pi B+, although the pins on the GPIO needed for it are already taken up by a RaspBee module.
Are there any other options? Could a JST to USB work?
The warmup time of the MH Z19b is 3 minutes. So 2 is probably fine, but you could probably do 3 just in case. Although 2 would save your more battery time.
Do you mind explaining your setup a bit more? I would love to do something similar but I do not know where to get started with the PIC microcontroller!