HI JP,
There r always some good points which strike us regularly whilst we write an essay, and if ur trying to fit every thought of ur's then i guess u will have to refrain from that habbit. Anyhow this was how i worked it out
30-25 Min - Brainstorm
No matter what happened i use to start writing the essay by at most 23rd min.
I always had a plan to write 4 paragraphs so i divided it like
23-20 - Introduction
18-10 - 2nd n 3rd paragraph. (All these points were from the brainstormed sheet. If i had any striking points i never tried to fit them, instead wrote it down on the rough sheet)
9-7 - for the conclusion.
No matter what happen's remember u gotta proof read ur essay. So try to read is AFAP and if ur still left with time then go back to the rough n pick up some points which i wrote down whilst i was writing the essay n fit them in relevant para.
Jst wish it helps