I seem to be talking for him, like, his response to my words will come out of my mouth instead of just being in my head.
Am I doing something wrong?
That sounds like parroting. You should avoid doing that when you're talking to your tulpa. I think basic narration just involves talking to your tulpa and not thinking up responses for it. The descriptions i have read of when a tulpa actually talks sounds like it produces an alien feeling meaning that you pretty much know you didn't think it. If you've only been doing this for less than 10 hours i don't really think your tulpa is sentient and talking yet sorry (I guess it could happen just unlikely). Even the veteran tulpaforcers tend to take awhile to make another tulpa.
Also lol I really didn't write that text wall to attack Kochie i wanted to stop people from getting confused about tulpa since there are some vauge points on the op that implies certain things that aren't true. I was kinda tired from my SAT test and maybe i sounded more aggressive than i thought sorry about that.
I don't know if Kochies Luna is even a tulpa (There is a point on the first mlp thread on 4chan where someone comes in with apparently a tulpa that just appeared though). It certainly wasn't created in the normal way for tulpaforcing. I think he claimed somewhere on the mlp thread here that it appeared.
Oh god more words how did this get here i am not good with computer.