How long do most of you wait before you start using the GI Bill?

First question is what is your goal? Make this fit your goal. If you still have more school you can look at the guard or reserve which may cover most tuition

I transitioned from active duty into a 2nd semester freshman. At the time I did not know what I wanted to major in, but I knew that I wanted to get my degree. Because I was considered a "transfer" student, I utilized that first semester to get a feel for what courses I had an interest which led me to declaring Political Science as my major. I am now exhausting my GI Bill benefits to pay for my Masters in Public Administration, and will have a BA and MPA while incurring zero student loans. Everyone's situation is different, and my personal goals were to effectively utilize my education benefits. God knows we've earned them, so use them.

I wonder if maybe "re-framing" your situation might enable you? Perhaps ask "What is it that I want to do?" and the follow-up will be "How can I use my GI Bill to make this happen?"

Just a thought, I'm available off-line if you need to chat.

I didn't wait.
I retired in Feb 06 and I signed up for classes in Dec 05 when I was on Term Leave. When classes began I was still on and sweating a recall.
The day I retired I took a bottle of Champagne to my repealing class. Then I found out not only were the classmates under drinking age, they didn't even know what Champagne was.
I used my G.I Bill home load while I was on Active duty stationed at Fort Bragg, N.C. in Aug 1991