Clive, I can't brake as late as Dimitar either, but you're wrong to think he gains 0.5 sec per corner by doing that. In fact I think he's losing a bit of time overall by braking too late for most of the corners, because it compromises how early he can put the throttle on. I've been trying to convince him about it for a year now
I managed a 51.5 twice during practice, so he was still half a second or more slower. It's just that I couldn't repeat any of that during qualifying.
When I was watching you drive in practice, I noticed that you use WAY too much throttle under braking, which prolongs your braking distance, and you also carry too little speed through most turns, especially the chicanes, taking them at cruise speed rather than at controlled deceleration or acceleration.
As a whole, with this car, it's imperative to really keep it going, because it is so heavy that it doesn't turn well on its own and it tends to lose a lot of speed, especially when the revs drop. It's a constant dancing with the throttle to keep it rotating, but it has to be delicate and just enough, with the steering wheel giving secondary inputs to correct the direction of travel.
It's difficult to give exact tips by chat alone, without being physically present to see the actual inputs you're doing with your wheel and pedals, and talking with each other. I'm pretty sure just about anyone here can improve massively if they can be shown certain aspects of how to do things.
Dimitar's style is very particular in that he likes an understeery car and compensates for it by turning in sharply, so it doesn't work for anyone. I can rarely drive his setups and usually opt to go for more neutral or oversteering settings, as I'm used to less steering input from my GPL years. If that's what you also tend to do, then you really have to focus more on exploiting the way the car reacts under braking and acceleration, with modulation of both pedals. It's where the key is, in my opinion.
Most of you guys, from what I could see, were driving this like a road car and not a racing car. You just let it roll too much on its own and don't force it into turning faster and keeping the speed through the turns. I wish I could record some videos where I could explain and demonstrate all these things, but I'm really bad at doing such things verbally, plus my room is a mess