When to test

Please answer somebody. I was suppose to start my period today, well temps still high and no sign of AF. Cervix high , soft etc... Anyway, I have a 12 day Lutheal phase so therefore I'm only 12 dpo, is it too early to test even though my period is due? I don't want to test and be dissapointed by false negative because I'm only 12 dpo. I just need some good advice please