from Adn to Bsn... please help ...

hello there everyone, i just joined this site. i have been debating on becoming a nurse for a year now.. ive been going back and forth between nursing and sonography. if i don't get into the sonography program, i will pursue nursing. but i have a question, i am a single mother, so for me, i need the quickest route to attain my rn license and start working and that would be thru getting my adn.. but my ultimate future goals consist of wanting to get into administrative or management positions and not just stay on the floor. so i was just wondering, how many more years would i have to go back to school for and what would the steps be when i do want to pursue my bsn after working on the floor with my adn for a few years? thank you, i appreciate the help...