There are several schools of thought on that. I would suggest watching a video or 4 on how people wick it.
What I do is I take the deck out of the atty entirely (it pops out when you press it up from the bottom after removing the top) so I can get at the bottom of the deck.
Then I wick it long and push the wick all the way through the juice channel so the ends hang out the bottom. Then I cut them off with a scissor as close as I can (1/8th to 1/16th of an inch maybe, or a few mm if you live in the rest of the world) then I fluff the stubble at the bottom of the deck and make sure it covers the entirety of the hole. It is possible to have too much cotton in there. You don’t want it too tight. Then I put the deck back in the bottom, juice up both the wick and the channel in the base, and put the top back on. Works pretty reliably. If I get dry hits after a few puffs it means I used too much cotton and I need to wick it again using a little less.