Full time is easier, but the hardest is when you only want something like 10 hours or 5. Twenty is usually workable, but if you think they need more, schedule that. You have to allow for downtime. Nobody wants a low paying job where every second you are supposed to be cooking or bathing or doing light cleaning. Factor in allowing the person to sit and chat or even check their phone. It's much easier to keep a worker happy and pay for more hours than to expect a lot, try to get a bargain and keep having them adjust to new workers while you worry if this will be the one who loses her temper or steals.