Where to start?

The best would be to start looking as soon as you can. It's not very easy to find good and affordable housing in Paris (whichever area you decide to go to - I would advise you to broaden your horizons there, and look around your favourite area too).
It can take quite long to find something, and places you will visit may not be free immediately, so the sooner the better! And don't forget that you will have to gather quite a few documents to give the rental agency, especially proof that you can pay the rent!

Thanks for the thoughts, to follow up with them what documents will I need? And do you think it would be better to rent an appartment for a few weeks online, then will I am there and able to go look at places and areas find an apartment that will suit me better.

Otherwise I will have to find and trust that an agent will be able to help me until I get to Paris. Which is a little scary sense I don't know anyone.

Merci,
Tabatha Chase

It's very hard to find weekly rentals in France (exept holiday rentals of course). There may be possibilities but since I'm not a parisian I can't say where you could find these, if they exist.
By the way, in France leases are usually 3 year leases (of course you can leave before that if necessary), bear that in mind.
As for necessary documents, you'll need proof that you have a job and pay slips. Not being French, you'll probably have to prove you are not illegally in France. And you'll need enough money to pay at least the equivalent of a month's lease - maybe even more.
Good luck!