Too soon?

Arrrhh!
This is what is running through my head as i am editing and reshaping my first chapter for submitting for the competition.
I knew as i was writing my WIP i would have to edit and rework it but i was hoping to not have to until i'd finished and now i am doing it before i'm finished.
Am i doing it too soon, or will it make it stronger now?
Anyway, i'm cutting out quite a lot from the beginning as it has way too much of that dreaded backstory! Inevitable when you are working with characters who have a past, and a newbie writer :)
Now i'm trying to filter it in so it is more 'present' and makes sense while keeping the tension, and hopefully readable.
What do you think the word count should be for the first chapter? The conditions for the comp said no more than 10,000 but i think this is too many words for a first chapter personally, so do i do half this or do the whole lot???
Arrrhh!!!