I understand many would have given advice do not worry about design doc in the early days of the product journey, focus on shipping features. I find this advice bullshit after a few years of product development.
My experience suggests without the design doc from the very first day UI becomes a sandwich. Every new component gets crafted with the mood of the developer or team. When a new member joins, he comes with his own learning and further additions.
Since there is no standard the same component inside the product starts giving a different way, approach to execution.
Even if you are starting, you have a 2 member team, you have no clue how and what you are shipping in 1st version. Get a fucking design doc that has minimum information about it.
- Fonts to be used
- Sizes of fonts in different places
- Actions on the buttons: close, open
- How will components behave, ope when clicked
- How will navigation bar, sidebar appear in various devices
- Fixed limited colors to be used across product
Please note as the product upgrades with time so do the design document. Do not fall in the trap of redesigning UI every year because it is fucking painful.
I am sharing this with my experience. I am in the middle of it right now. I might sound grumpy, but this is how it is.