ive had my lip pierced at a 16g for 4 months. i want to move to a 14g. How much longer should i wait before i attempt to stretch it? how would i go about doing this?  i have a 14g steel taper. do i use the same procedure as i do with my ears? will i be able to switch back and forth with a retainer after a few days like i do now ?

Give it a few more months. You may not have to use a taper, but you can if you like. If you need to start switching it right away, you could use glass to stretch with and leave it alone for a bit to allow the new stretch to settle.

 Stretching with the glass sounds like a great idea. What on this site would work?

Kaitlin N:

i stretched my philtrum to 14g from 16g when it was about a year old. it BURNED since we tapered it, but it wasnt horrible. i wore an IS piece in it when i was 14g, and 16g i wore neometal

Well, from the context of the first post, I'm assuming it's a lower lip piercing. Everyone I've ever spoken to says that lower lips are much easier to stretch than philtrums, so I wouldn't expect any real pain from it.