Bobcats can be called anytime of day, though I think the first and last hour of sunlight are preferred.
Try some high pitched sounds, like bird or some rabbit in distress, be patient.
I've have way more coyotes come in to the call than cats. So, that's what I would expect. Being in a cat rich envionment will deffinately help.
Mine tended to sneak in, but most people I know say they just sort of show up.