If you were healthy enough to use the sauna preop then I would imagine you could resume your pre op habits. Just to be on the safe side, best check with your surgeon to maintain his post op protocol. Best wishes
At one month after liposuction, a sauna or hot tub should be enjoyable. Assuming the small cuts healed well in the first 1-2 weeks. Your skin numbness should be waking up, but make sure nothing is hot to touch.