When to harvest sweet potatoes

[HiPoha]

I planted a couple of sweet potatoes in a half barrel container in early June. Used store bought potting soil and compost mix for the growing medium. The potatoes seem to be doing very well judging from the vines growing out of the container. There are vines coming out of the soil from places other than the seed potatoes, so I assume there are potatoes under them. It's been 5 months now. Should I harvest them now?