When to tell a potential employer about my gender status?

[maybelaterlouis.livejournal.com]

Cross-posted from ftm_youth.

Anyways, hi. I'm Louis, male-identified, and sixteen. I've had this question on my mind since I last applied for a job (unsuccessfully). Although my parents don't try to sabotage my transition, they do not support me-- so I have not had a legal name change, and will be unable to get one until I'm eighteen. How do I bring this up to potential employers? On my last application, I put down my birth name with my male name in parentheses, then explained the situation in brief to the employer during my interview. Is this the best way to go about it, or would it be possible to put down my male name and only explain the situation if I get hired? Or should I only put down my birth name? Does it make a difference if the application states the company will not discriminate based on gender identity?

Thanks.