How long can I leave beef casserole in the slow cooker?

[fatsatsuma]

Can I put it all in and switch it on (low? auto?) tonight, and leave it cooking gently until lunch tomorrow? I want to get it sorted tonight. I know I could do the prep tonight and switch on in the morning but I'm not sure that 4 hours is long enough cooking time from cold, and I don't want any faffing around heating things up in the morning.