Missed Miscarriage

Hello everyone. I am currently 9 weeks although after my ultrasound today I found out I have a missed miscarriage. No heart beat. Although I'm taking it very well since I already have 2 beautiful boys. My Dr prescribed me Misoprostol the pill you take to help you miscarry faster. My Dr said it would only take about 1-3 hours to happen. Its been about 4 hours and nothing. No cramping no bleeding. I was hoping it would happen right away. Has anyone else experienced this situation? Do you have any advice on how long it would take?