I think the miscarriage is about to happen

Question I have my D&C scheduled for Thursday at 4:00am i am 7 weeks pregnant from what the doctor said on Monday I went to the restroom and had light bleeding my stomach having bubbling like I’m about to start my cycle but it’s painless, have anyone experienced a natural miscarriage? Btw the doctor said mines is considered (missed miscarriage which could take weeks to miscarry) when do the full process begins? I’m scare if it happens while I’m teaching at work and I experience the intense pain