Good day. I have plenty of experience working with MCU-based embedded systems. I've worked at Freescale Semiconductors for half a decade as an engineer. I've worked with several arm-based microcontrollers (NXP, Atmel (now Microchip) and STs families) and, lately, with the esp8266 and esp32 family of microcontrollers, either with or without an RTOS.
I'd need more information regarding the exact specifications of the project, as well as your expected timetable. However, I can say the time stated is more than enough for finishing a functional prototype and having a long enough testing phase.
Regarding payment,of course, none is required before a proof of work (firmware, PCB design and other related documentation).
I'd find quite useful for the both of us, if you'd find the time to talk a bit further regarding your project's requirements.