How long is the missed miscarriage process?

Hello everyone. This is my 5th pregnancy. I had one miscarriage and went on to have three living children. I went for an ultrasound at what was supposed to be 9 weeks exactly. The baby only measured 6 weeks 3 days, and they couldn’t find its heartbeat. They scheduled me to come back a week later just to make sure I didn’t get pregnant later than I thought because my period is irregular. I have been having blood tinged mucus the whole pregnancy but it’s barely noticeable. Well today it’s the same, and I’m still extremely tired and nauseous, with mild cramping.

In your experience with a missed miscarriage, how long did it take your body to figure out what was happening and pick up the bleeding?