dd1 started getting it when she was around four and understood what money was/what it was for. She is never forced to save it, but is encouraged too and often does. She feels proud, when manages to get enough to buy something she wants.
She doesn't get a set amount, but earns it. If she does her spellings without a fuss, she will get £2 and then particularly good behavior is rewarded such as cleaning her room without being asked to. By cleaning I mean cleaning. She is expected to keep it tidy as par of the course, but she is not expected to mop/dust etc and is rewarded if she does. If she collects her uniform in and puts in the washer half way through the week, when she is running low on uniform, she might get another 50p.
She doesn't often do chores, but if she is looking forward to buying something and knows she is getting close to her target amount she might come and ask what she can do to earn extra pocket money.