I am attending graduate school in Bangkok.

My ED Visa is coming up for its second renewal. Due to some scheduling issues, I need to renew more than 30 days prior to the expiration. Is this possible?

The ED Visa I have now expires on 15NOV12, and I would like to renew it on or about 10OCT12.

The school will provide all of the ED Visa renewal paperwork I need starting on 08OCT12.

Is it possible to renew an ED Visa more than 30 days prior its expiration?

I will be using the main immigration center in Bangkok.

You can always try. if there is a good reason to do it early they often extend earlier than 30 days.

I always try to go for extensions on any type of visa I may be on Non B, Ed Visa etc., 30 days or 21 days before, incase I am missing a document or something is just not right with immigration. Even if they were to tell me to come back, at least I will know where I stand, not leaving things to the last moment.

Has anyone first-hand experience with successfully renewing an ED Visa > 30 days to the expiration date?

I doubt anyone in graduate student status has had that situation (and that may make your chance better). I suspect most full time students would not have an option to be missing from classroom for an extended period of time in the view of immigration so less likely to be approved. The best you can do is apply with proof of travel/reasons and try - if not obtain a new non immigrant ED visa for your return and start the extension process again 60 days later.