Teemo blind not being applied immediately

I've been trying out Teemo jungle in a few custom games and I've noticed that the first attack on me is still landing when I blind something. At first I thought it might be a timing issue, there were one or two times when I cast blind to initiate but an autoattack would land before the blind did, but when I tested it today blind definitely isn't being applied immediately when it lands. To test it I was standing in melee range of a camp so they wouldn't have to move to attack me, cast blind to initiate combat then immediately hit S to stop all actions so that nothing other than the blind could be starting combat. Every time the first attack on me would land and do damage, the second attack would miss.