Hcg dropping, when will bleeding start?

Asmi • Hopeful for the best to come!

My hcg has started dropping. I m just 4weeks 6 days but we had two 5 day blastocysts transferee as IVF. Doctor asked to wait few more days and see if bleeding starts and it resolves on its own. When do u think bleeding will start? I have stopped all IVF meds and so far no spotting or bleeding. All pregnancy symptoms have gone now. Pls help. I don’t want to get this to ectopic and laparoscopic or other serious stuff.