Alright, so I'm fifteen as of yesterday.
I got my ears pierced for my birthday, yesterday,  and I would like to stretch them. I read the "How young is too young?" thread and I'm sure many of you disapprove. My mother isn't too keen on the idea, fyi. I don't want to rush anything and be stupid about it.I guess normal peircing is a size 18g, according to research. How long should I wait to go to a 16g and how long should I keep the 16g in to switch to 14g? 

 Well, you're starting off on the right foot by asking questions and seemingly wanting to go about this correctly. Here's BAF's stretching guide: http://forums.bodyartforms.com/forums/t/5641.aspx

you need to allow your new piercing to completely heal before stretching

wait 6 months to a year

also, 15 is very young to be doing something like this to your body. i started stretching my ears when i was in 8th grade but someone advised me to stop wait a couple years and if i still wanted it get it then

it was the best advise they could have given

these sort of things last forever if you want them to, give it time before you rush into anything.:]

 15 is not too young to actively seek out information for correctly stretching a piercing. In fact, I already like this kid, because his post didn't say, "im 15 and my mom said no but i have inch gages she just doesnt get me i hate my parents." 

OP, I'd stay go ahead and stretch 6 months from now. If you follow the guidelines, like you seem to want to do, you'll be around 4g or 2g when you turn 17, and I think that's totally acceptable. The best thing about taking your time is that you learn what you really want, and you can show everyone how responsible you can be.  Just follow the guideline thread that was posted, and you'll be fine. :) 

 I agree with Eric.  If you just take your time and be patient, you'll still have plenty of time to really see if you want to commit to the larger sizes.  If, say in a year or two you're not happy with it, you'll still be able to take out the jewelry, and retire your piercings, and they'll still probably close up.  On the other hand, if you do go too quick, you're going to tear something, and it's going to be very problematic, not just for future stretching, but scar tissue and shit sometimes shows up when you retire piercings.