I used -4 BB for this lap you should use somewhere around the same because if you dont you will kill your front tires even in a 15 minute race and loose a lot of time in the last 2 laps.

T1 go late on throttle bcs of the exit offtrack watch out there is a lot of understeer in that corner so make sure to slow down enough 
T2-5 go for a late apex and watch out to not hit the curbs so you can get a better run 

T7 dont hit the curb on the hairpin as you will get oversteer or loose the rear under acceleration 
T10-11 dont hit the inside curb on T10 on T11 you can cut the curb slightly without loosing time 
T13 watch out to not hit the outside curb on entry and the inside curb on the apex

T15-16 dont cut the curbs you can drive on them but dont go over them as you will loose a lot of time 

T17 make sure to brake early enough then you will have good rotation

Generally you should be making sure to shift just before the car hits the limiter as that gains you a lot of time in the McLaren!
Driving wise you should make sure to have a peak braking pressure of just under 100% so in the range of 90-95% and then trail of that peak pressure as soon as you start moving your wheel.
And once again as a reminder this is a fixed setup series so the only thing you can adjust is the brake bias for which i will always provide the setting i used!