That's why it is so important to know the current system.Immigration bars are based on the time periods of "Unlawful Presence"."Unlawful Presence" does not begin until the age of 18.If you have accumulated more than 180 days of unlawful presence after reaching 18 you have effectively lost your chance at wiping your slate clean as it relates to immigration benefits.Once a person has reached after the 180 day mark after age 18 the 3 year bar comes into play,and once it reaches 1 year of unlawful presence when you reach your 19th Birthday the 10 year bar then comes into play.

The OP is currently under 18 with a pending petition for permanent residency therefore should not have any issue acquiring the benefit at the US embassy in their country of origin if left before age ~18 1/2.The benefit of permanent residency once acquired at the US embassy showcases the OPs right as a resident of the US to legally enter the US without issue.If they wait any longer the petition could be considered abandoned and will more than likely be illegally in the US for the rest of their lives until Federal laws have changed Comprehensively or Dream act has passed........which is a complete unknown at this point !
According to the law,you have no immigration bars therefore I see no reason why you shouldn't get the benefit.If you wait too long you could have your petition considered abandoned AND you would then acquire a 3 year bar if over 18 1/2.

I would also suggest flying because it would be reflected in the system that you had left officially AND you would have ticket stubs proving so as well.