I just sort of make it part of my routine on wash day. Once I'm done w/my final rinse I then go and part my hair in 4 sections again, apply water and my whipped shea butter to each section, detangle and then put it into a ponytail close to the center of my head. From there I will either tuck all 4 ponytails under and towards the center to make a bun or else I will pull all 4 pontytails through my bun maker and wrap them around it, tuck in the ends and secure w/another ponytail holder on the top.
Then each day I have the bun in I just spritz w/my distilled water & grapeseed oil to moisturize. I too was concerned about the whole wet bunning thing but it has never been an issue (knock on wood). However think about it this way...you should only comb/detangle your hair when its wet w/conditioner anyway so why can't you do the same w/water & whatever leave in you choose?