Warwick Eternal Thirst Stacking

Warwick's Passive is described as: Each of Warwick's attacks will deal 3 / 3.5 / 4 / 4.5 / 5 / 5.5 / 6 / 6.5 / 7 / 8 / 9 / 10 / 11 / 12 / 13 / 14 / 15 / 16 additional magic damage and heal him for that same amount. Each successive attack against the same target will stack this amount of healing and damage up to a maximum of 3 stacks. The stacks remain for 4 seconds.

Do the 3 stacks include the first attack or start stacking afterward? For example, at level 1, Warwick's basic attack is 62 (assuming no attack damage masteries, runes, or items). If I attack someone 4 times, would the damage done be 62 + 3 (65), 62 + 6 (68), 62 + 9 (71), 62 + 12 (74) and then stay at 74 while I continued to attack or cap at 71? And when the 4 seconds are up do the stacks reset completely (i.e. for simplicity attack speed is 1.0, I attack 5 times, would the 5th attack be back at 65)?