I'm not ready to fully do my taxes right now. I just wanted to sign up to get the discount. Will I get to restart where I left off?

You can start now and your work will be saved. You will pay the price that is in effect on the day you file and pay.  That price goes up during tax season.   The only way to guarantee the price is to pay for TurboTax even if you are not finished with the return.

In order to get the "early bird" discounted fee for online TurboTax you need to pay before March 1.  The fees increase as of March 1 every year.  You do not have to file when you pay.  Paying your fees does not file your tax return.   Your return is not filed until you go all the way through the FILE section and click a big orange button that says "Transmit my returns now."