First of all, to be ready in a snap, you have to know your closet. And you closet has to be organized. Things have to be cleaned and in their place so that you can count on things being where you expect them to be. Otherwise, you just waste time looking for things that are in there.
So, assuming things are clean and your closet is organized...
You are looking for a casual look to pull together in 15 minutes.
Basic jeans and a shirt. Distressed boyfriend jeans and a soft, oversized cotton top to pull on. Keep your accessories simple and classic. Your top is yellow and beige. Your shoes are yellow and beige and good, basic flats with details that add edge. The handbag is ivory, yellow and beige and adds fun. Your gold hoop earrings and watch are basic and gold. Add the white panama hat with a ribbon to match your jeans and sunglasses to match your hat.
Simple, classic, good looking and now you even have time to brush your hair and freshen your lipstick before your friend picks you up to go for coffee! Enjoy!