With my HG pregnancy I started feeling it about 7DPO (so probably implantation time) then by the time AF was due it had totally disappeared. I'm not sure when it reappeared but I know by my first appointment at 8 weeks I had already lost 7kg so I am thinking MS came back around 5.5-6 weeks and vomiting starting about 6.5-7 weeks?
I know how you feel though, I had a close call recently and I was half exciting at the possibility of a non-HG pregnancy and half scared that it wasn't going well.