I applied in-person. The process took 6 months. I interviewed at US Army in Jun 2009
Interview
To become a Warrant Officer in the US Army you have to have five years military experience in a Military Occupational Speciality (MOS) that feeds the Warrant MOS you are going into. For a Targeting Technician that is most Field Artillery MOS. Then you have to submit a packet, which is reviewed by a board to determine your elegibility. Lastly you have to have a senior Warrant Officer in the field write a letter of recommendation.
I applied through a recruiter. The process took 4 weeks. I interviewed at US Army (Des Moines, IA) in Nov 2009
Interview
Meet recuiter, they will treat you like a best friend. They will drive you to there main processing places and run you through tests. Then you will get a contract and dates to leave to basic.