How long will i go to jail?

ok so a cupple of months go i got arrested for ault with a deadly weapon i was 16 at the time i pulled a knife on my step dad i did not try and swing it at him i just had it in my hand in case he hit me and i want to know how long i will go away for i have 6 months of probation and then i go back to court i have nothing on my record this was the first time iv ever done anything to get in trubble with the police.iv have just turned 17 and i was wondering if they will charge me as an adult also.