Takes me about 4-6 hours to memorize a 1.2k word essay perfectly. The method I follow is:
Memorize sentence by sentence, for each paragraph. So read first sentence, memorize it, then add on the next, memorize it, then add on the next sentence, and memorize it until the whole paragraph is memorized. Then add on the next paragraph (go again sentence by sentence, once you get the first 3 sentences memorized in the 2nd paragraph, stop adding the first paragraph with it).
After this, memorize half the essay fully, write it out, and fix up any mistakes you made. Then do the same for the 2nd half of the essay, and then all you do is add them up at the end, takes 6 hours max in 1 sitting.