Transportation route between Waterloo and Guelph (Ontario)?

I can't drive, and I can only carpool occasionally. On those days that I can not carpool, how can I get to Guelph with a flexible schedual? (e.g. greyhounds get there at 6 and have to leave by 9, that's not flexible, if I miss that bus, I'd have to wait till 1 the next day)