Replying to BIG Flips

So I want to land a really big backflip before the end of the season (possibly only one more weekend). I have no problems flipping on smaller jumps, and I don't just huck it...I know how to control it. My question is how to set the rotation at the right speed for the jump. I can see myself over rotating and getting fucked up really easily. I already stall out my rotation as it is, I don't know how I could stall it out even more. Basically, I would like someone with actual experience to tell me what exactly to do when taking off to get a nice, slow flip going without not setting it enough and getting stuck upside down. +k for actual tips.