There are a few things you can do to make the process of writing your application essays a little easier for yourself.
Adopt the following strategy or modify it to suit your temperament, but do something like this:
 Collect all your application materials into one pile and compare the essay topics you'll have to work on. Note the similarities and group together the applications that overlap in their requirements.
 Choose one essay to work on first, and give yourself no more than 8 days to come up with a complete draft. Stick to this time-line religiously: giving yourself a frame within which to come up with essay ideas can do wonders for those little gray cells up there.
 Don't wait till the weekend to do the first essay. Make it a Thursday or a Friday, or whatever, but don't do it on the weekend because if you do, you're likely to revert to that blanked out slo-mo state that is the bane of all essay-writing.
 Jot down any ideas, phrases, sentences, dialogue bits that come to you in the next few days. Don't bank on being able to remember them cold once you sit down to write. Note them down as you think them up.
 Within the 8-day period, give yourself 2 days to write a complete draft of your first essay. Don't wait till day 8 to start drafting it.
 Once it's done, put your first essay draft away for a couple of weeks and begin to work on the next one.
 By the end of four weeks, you'll have complete drafts of four applications and you can then begin to revise essay number 1. During the preceding four weeks, you'll probably have come up with more ideas, some refinements of what you've already written, ways of expressing yourself more clearly or more strikingly or simply better.
 Do at least 2 revisions of each essay, but make sure to space them out by a week or so in order to be able to see them afresh when you return to them.
 Have a teacher or one of your parents or perhaps an older sibling or your aunt and uncle read the essays and tell you what they think of them. Consider their feedback as objectively as you can and incorporate the suggestions that you believe will make the essays  read better,  represent the person you are more faithfully and accurately,  capture the reader's interest more securely.
 Have a third person proofread each essay for spelling and punctuation errors, send the essays out and get ready for a long wait.