I know canned yams are already soft and really shouldn't be used in a crockpot, but I have a pitch-in at work and I would like them to be warm for the lunch. I arrive at work at 6:30, have a 15 minute break at 8:30 and then eat lunch at 11:00. If anyone could let me know when I should start them and whether to put them on high/low - I'd appreciate it!