I blend mine off and on until it's pretty much just warm to the touch (when I add my FO). By that time its thickened up enough and good to bottle. I don't cover with the bottle-top until completely cooled, though. Until then, I just lightly cover over the tops of the bottles with a clean paper towel to prevent contamination by dust, etc..
I blend for 30 secondsish, then let it sit for like 20 mins. then blend a bit more and I keep doing this until there is no frothiness on top. I use guar gum in my recipes, so I think that contributes to the frothiness. I also let mine cool completely before bottling.