With my naughty mini i put a few drops in the top of the coil head and then let the filled tank sit for 15 min. 15 min is probably more than needed but i like to make sure its soaked in. Its best to start at a lower setting and work your way up.
There are vids online on how to rebuild the coils but it was a little too fiddly for me.
Its a nice little tank and tastes great, I got one of the replacement mesh
tanks on mine, it looks nice and i feel it may be a little more protected if i manage to drop it.