Asking out girl at her apartment doorstep/roses and gift?

Ok there is girl I love and I have already talked to her and slept with her in her bed. The other day I left her 12 roses on her apartment back porch and a love letter and her favorite cigarettes. She has not called me back. I talked to her cousin and he said to do what my heart tells me to do and too listen to my heart. So when I came by her apartment I knocked on her door and she was obviously not home and also I knew she was not home because her lights inside were not on, and there was an apartment newsletter on her door knocker so I knew she was not home so I left. I'm planning on going back to her apartment and I hope she is there. But what if she not there? Should I just wait there? I let her neighbor now I was leaving her a gift and did not mean her harm. I want let her know in person how I feel about her. Is sitting outside her door waiting for her a bad idea? Or does it show I really have fallen in love with her. Please give me honest solutions to help me.