My 11 year old noticed some blood on her underwear. Her actual period shouldn't be in about another 10 days

Blood in underwear. The blood may represent a period because at her tender age the menstrual may not have stabilized yet. Another consideration is to have her urine checked to rule out a urinary infection.
Could be normal. It is not uncommon early on to have an irregular period. If she starts her period and it is normal for her there should be nothing to worry about. She should see her doctor for any symptoms that are out of the ordinary such as increased pain or heavy bleeding.