Me too. I have finally gotten it thick enough to not have butt burn, but I'm still getting up every 30-40 minutes all night. I'm 8 weeks out of takedown. 

Hi, You dont state how long you have had the J-Pouch or if it is for solids or wind or both (most likely).

In my experience (22 years post J-Pouch) there is no definitive answer to this its just a matter of not eating or drinking too late in the evening.
I personally find a probiotic yogurt on an evening helps me. I dont know if the probiotic or just the yogurt that helps.
You could speak to your docs about things like charcole tablets to thicken things up and absorb the gas but be warned as they can have adverse effects if not careful.
If your J-Pouch is very recent you will just have to be patient as the interal swelling goes down and your body re-learns how to control your new bowel. In my experience it took quiet a while.

This has been written about many times here. It might be best to start by searching for some of those posts.