With clothes, I started when DD was 3 I think, offering her a choice between two items of clothing (any more and it was too overwhelming for her). Now at 4 she chooses her own outfit independently.
With meals, the amount of choice she gets varies. If she's in the kitchen with me I might ask her which vegetables she wants. With snacks, I will often just ask her what she wants. Sometimes she can tell me straight away what she fancies, sometimes she wants to hear a list of options (even though the options are usually pretty consistent), and sometimes she just likes to have a few options on a plate. My lovely SIL allows her DS to choose his tea every night which often means she's making two different meals, so I'm avoiding giving DD that much choice until she's old enough to cook independently (at the moment she often helps with prep, stirring, etc.).
I try to give her options for daily plans as often as possible, but it depends what I need to get done on any given day. She's an only child at the moment but I'm currently pregnant so in the future her input will have to change.
It definitely takes longer when a child gets to choose initially, but as with anything, the more they practise the better they get and it takes a lot less time so my advice would be to start small and gradually build up how much they get to choose.