Typical Hardware Development Timeline

System Architecture

1-2 weeks
Selecting chips, purchasing development kits, calculations, simulations, pros/con tables

Schematic Capture

2-4 weeks
Get a modern PowerPoint Presentation that is beautifully designed

PCB Design

3-8 weeks
Creating all footprints and 3D models for all parts, defining stack-up routing all connections, running DRC check, exporting PCB for fabricator

Prototyping

1-2 week
Assembling quantities of any size in-house (1 to 100), to ensure the manufacturing quality is up to my own standard and all devices work.

Firmware

4-8 weeks
Test all peripherals, writing drivers for specific chips (e.g. ADC, LCD, LEDs, Wi-Fi), and system specific code

Testing & Compliance

4 weeks
Testing prototype for any changes, testing in the field, identifying EMC and Safety standard requirements, pre compliance and formal compliance

Production

2 weeks
Optimizing BOM and PCB panel, quoting from manufacturers, creating test procedure, and designing a test jig.