How can I find out how long a property has been on the market by just looking at the

I am helping out my sister-in-law to purchase a house. She needs a house with four bedrooms and two bathrooms. She wants a house with a large space for a garage and she also wants a backyard for her gardening activity. How can I find out how long a property has been on the market by just looking at the listing? What does BMK stand for? Is it Bank Owned?