I don't. For web apps, I throw uncut, raw and basic app online and see if it rolls. When and only when I start getting signups and questions whether it will do

I don't. For web apps, I throw uncut, raw and basic app online and see if it rolls. When and only when I start getting signups and questions whether it will do X or Y, then and only then I start thinking about design. I usually end up with either ripping ideas from some themeforrest theme and going my own route or just buy the theme and be done with it. Same for icons. Bottom line is not to waste time.