You will notice that the pre flowers at the node connections will swell and get bigger and the pistols will shrink back in... the buds will start to appear where new foliage would appear, where in veg new shoots would form from the nodes.. they will now 'stretch' and then fill in with many pistol/calyxes stacking on each other... that is the 'bud' and what you love to watch grow fatter and fatter.