TL;DR: I have most of what you need already available or mostly done. I can work on the project before you even accept this bid. No strings attached, you can pay after that, this way you can see how I work without taking any risk. Just let me know and let's talk specifics.
Good day, I have plenty of experience working with MCUs (mainly freescale and STs families), especially with arm-based ones and lately with the esp8265 and esp32 family of microcontrollers. I've worked at Freescale Semiconductors for half a decade as an engineer.
I'd need more information regarding the exact requirements of your project. However, for what I understand at the moment, I can say the time is more than enough for finishing it and having a long enough testing phase. I have already most of the hardware and software available because of previous projects.
Of course, all payment can be after the delivery of the firmware. Also, I can work on the project before you even accept this bid. No strings attached, you can pay after that, this way you can see how I work without taking any risk. Just let me know and let's talk specifics.