Windows Update Issue SCCM

[Lorfarius]

I'm having a bit of a problem with Windows Updates and scheduling. Every month after update Tuesday I wanted the updates to happen at 6pm on the following Friday, basically when everybody is offsite but what seems to be happening is every Wednesday morning around 10am each month the updates are being installed and the workstations restart. Always seems to happen during busy classes and I have very angry teachers coming up to complain! I've been through all of the GPO's on the DC but this is the only thing related to updates that's running:

 

 

Over on the SCCM server I've created a fresh deployment rule and disabled the others (except for Endpoint but that doesn't touch WU in any shape or form). Looking at this I'm starting to think the first option (as soon as possible) might be causing it:

 

 

To try and get round this last month I surpressed the restarts but on the Wednesday after Update Tuesday the updates were installed:

 

 

I'm probably missing something obvious I'm sure but can anyone help? The PC's are all running Win 7.