We started when the kids were around 2 to help pack their toys away.

Now DS is nearly 5 & DD is nearly 3, we ask a bit more of them. DS now makes/straightens his bed in the mornings, puts his clothes in the laundry, tidies his room, puts his dishes in the sink and helps to tidy the lounge room. He also checks the letters & brings the bins in. The last two are his choice and he takes great pride in doing it!
DD mostly just twirls around trying to look like a princess & thinks she's too beautiful to do anything We're working on her but I think we have a fair way to go When she decides to help she puts her washing in the laundry & her dishes in the sink, she tries to help tidy up but usually just chucks stuff anywhere.